▸ dev.cosmolabs.org
Beautiful tools for developers
A growing collection of fast, shareable utilities for developers, designers, webmasters and engineers - plus a live showcase of CosmoLabs open source.
free forever · no login · 100% client-side
AI & Agents
21AI Commit Message Generator
newBYO keyPaste a git diff, get a conventional commit message from an LLM — bring your own free Groq key, called straight from your browser.
/commit-message-generatorSystem Prompt Builder
newAssemble a system prompt from ordered blocks — role, context, constraints, output format — with a live token count, soft-limit warnings, and a shareable URL. 100% client-side.
/system-prompt-builderAI Image Generator
Turn a text prompt into a 1024×1024 image with FLUX.1 [schnell] on Cloudflare Workers AI. No account, no API key — rate-limited for fair use. Your prompt goes to the model through our Worker; we store no prompts and no images.
/ai-image-generatorCache Breakpoint Planner
Find what your prompts share — common prefix and suffix blocks — and place prompt-cache breakpoints where they pay, with an estimated cost saving. 100% client-side.
/cache-breakpoint-plannerCache Savings Calculator
See what prompt caching saves — uncached vs cached cost over N requests, with the write-premium break-even point.
/cache-savings-calculatorChat Format Converter
Convert chat transcripts between OpenAI messages[], Anthropic system+messages, Gemini contents[], and plain Markdown. Roles map faithfully, tool calls are preserved where possible, and anything unmappable is flagged — never dropped silently. Runs entirely in your browser.
/chat-format-converterContext Window Planner
Paste your system prompt, docs, and history — see how they fill any model's context window, with overflow warnings and output headroom.
/context-window-plannerConversation Pruner
Plan how to fit a long chat history into a context budget — which turns to keep, fold into a summary, or drop, protecting system messages and the current request. 100% client-side.
/conversation-prunerEmbedding Chunk Planner
Plan document chunking for RAG — chunk counts with overlap math, vector counts, and embedding costs per model.
/embedding-chunk-plannerEval Metrics
The standard LLM-eval numbers with exact math — unbiased pass@k, precision/recall/F1 from confusion counts, exact-match and label-set micro-F1. 100% client-side.
/eval-metricsImage Token Calculator
Estimate the vision token cost of an image before sending it to an LLM - low/high/auto detail modes, the 512px tile math, the 2048/768 downscaling steps, and a full base + tiles + detail breakdown. Runs entirely in your browser.
/image-token-calculatorJSON Repair
Fix broken JSON - trailing commas, single quotes, unquoted keys, comments, Python constants, BOM and truncated documents - and get clean pretty-printed JSON plus a list of every repair applied. Runs entirely in your browser.
/json-repairLLM Cost Calculator
Estimate LLM costs per request or per month at billion-token scale — with realistic prompt-cache hit rates, four-lane pricing, and side-by-side model comparison from a dated pricing snapshot.
/llm-cost-calculatorMock LLM Responder
Generate deterministic mock LLM API responses - chat completion JSON, SSE event streams with chunk timing, and a replay curl - for testing clients without an API key.
/mock-llm-responderModel Picker
Filter every major model by context window, price, modality, and tier — sort by cost, context, or tokens-per-dollar to find the right model for the task.
/model-pickerRAG Chunk Comparator
Chunk one document three ways — fixed-size, sentence-aware, markdown-heading-aware — and compare counts, size spread, and how often boundaries cut sentences mid-thought. 100% client-side.
/rag-chunk-comparatorRate Limit Planner
Turn RPM/TPM limits into a concrete request schedule — batch size, spacing, binding limit, and total run time, with a safety factor for retries. 100% client-side.
/rate-limit-plannerStrict Output Validator
Check a JSON Schema against OpenAI structured-outputs strict mode rules — open objects, missing required keys, unsupported keywords — before the API rejects it. 100% client-side.
/strict-output-validatorToken Estimator
Estimate LLM token counts for any text or code - per-content-type heuristics (prose, code, JSON, CJK) with a ±15% range, plus chat-framing overhead. Runs entirely in your browser.
/token-estimatorTool Schema Builder
Build function-calling and MCP tool schemas that pass strict mode on the first try, and lint pasted ones against the strict-mode contract — additionalProperties, required-sync, defaults, enums — with one-click autofix for every mechanical violation. Runs entirely in your browser.
/tool-schema-builderVRAM Calculator
Estimate the VRAM an LLM needs — weights by quantization plus the KV cache for your context and batch — and see which consumer and datacenter GPUs hold it.
/vram-calculator
Encoders & Crypto
10Base32 / Base58 / Base62 / Base85 Encoder
Encode text to Base32, Base58, Base62, or Ascii85 - or decode it back. UTF-8 safe, runs entirely in your browser, with a shareable link to your exact input.
/base-encoderBase64 Encode / Decode
Encode text to Base64 or decode it back. UTF-8 safe, runs entirely in your browser, with a shareable link to your exact input.
/base64Basic Auth Generator
Build HTTP Basic Access Authentication headers from a username and password, or decode an existing Authorization header back to its credentials. UTF-8 safe and fully client-side, with a shareable link.
/basic-auth-generatorHash Generator
Compute SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text at once, using the browser's native SubtleCrypto. Copy each digest. 100% client-side.
/hashHash Type Identifier
Identify the likely hash algorithm of a hash string by its length and character set - MD5, SHA-1/2/3, BLAKE, CRC32, NTLM, bcrypt, Argon2 and more.
/hash-type-identifierHex ↔ Text Converter
Convert text to hexadecimal and hex back to text, with delimiter options (none, spaces, 0x, backslash-x) and full UTF-8 support. 100% client-side.
/hex-converterHMAC Generator
Generate a keyed-hash HMAC (SHA-1/256/384/512) for a message and secret. Runs entirely in your browser via Web Crypto, with a shareable link to your exact input.
/hmac-generatorHTML Entity Encoder/Decoder
Encode text to HTML entities and decode entities back to text (named + numeric). UTF-8 safe, runs entirely in your browser, with a shareable link to your exact input.
/html-entity-encoderOTP Code Generator
Generate time-based one-time passwords (RFC 6238 TOTP) from a Base32 secret, with selectable algorithm, digit count, and period - updating live, entirely in your browser.
/otp-code-generatorURL Encode / Decode
Percent-encode or decode URLs and query parameters. Choose component (encodeURIComponent) or full-URI (encodeURI) mode. 100% client-side.
/url-encode
Converters & Formatters
20JSON Formatter
newBeautify, minify and validate JSON instantly. Paste, format, copy - all in your browser. Share a link to your exact input.
/json-formatterCompound Interest Calculator
Project investment growth with any compounding frequency, scheduled contributions and inflation adjustment. Yearly breakdown, growth curve and CSV export — runs entirely in your browser.
/compound-interest-calculatorData Unit Converter
Convert between digital data units - B, KB/KiB, MB/MiB, GB/GiB, TB/TiB. Switch between decimal (1000) and binary (1024) bases, runs entirely in your browser.
/data-unit-converterDPI / PPI Calculator
Compute screen pixel density (PPI/DPI), dot pitch, physical dimensions, and aspect ratio from any resolution. Solve for PPI from a diagonal, or derive the diagonal from a known PPI - all in your browser.
/dpi-ppiIPv4 ↔ IPv6 Converter
Convert between IPv4 and IPv6 addresses both ways. Parse and validate addresses, expand and compress IPv6 to its canonical RFC 5952 form, map an IPv4 into IPv4-mapped and IPv4-compatible IPv6 (or any custom /96 prefix), and extract an embedded IPv4 back out.
/ip-converterJSON → TypeScript
Paste any JSON and instantly get clean, typed TypeScript interfaces - primitives, nested objects, arrays and unions, all inferred. Optional keys, reserved-word quoting, and shape dedup are handled for you. Runs 100% in your browser.
/json-to-typescriptJSON ↔ CSV Converter
Convert a JSON array of objects to CSV and back. Handles quoted fields, embedded commas, newlines and escaped quotes (RFC 4180). 100% in-browser.
/json-csvJSON Minify
Remove all whitespace from JSON for the most compact serialization. Validates as it minifies, runs entirely in your browser, with a shareable link to your exact input.
/json-minifyJSON to Zod Schema
Generate Zod validation schemas from JSON. Infers z.string, z.number, z.boolean, z.object, z.array, z.null, and z.union for mixed arrays.
/json-to-zodList Converter
Transform a list between separators (newline, comma, space, pipe, semicolon, tab) with trim, dedupe, sort, and empty-removal options. Runs entirely in your browser, with a shareable link.
/list-converterList Set Operations
Compute the union, intersection, difference, or symmetric difference of two newline-separated lists. Deduped results with optional trim and case-insensitive matching. Runs entirely in your browser, with a shareable link.
/list-set-opsMarkdown Table Generator
Turn pipe, CSV, tab, semicolon, or space-separated data into a clean GitHub-Flavored Markdown table. Auto-detects the delimiter, pads columns, escapes pipes, and supports per-column alignment - all in your browser.
/markdown-tableMath Evaluator
Evaluate math expressions - arithmetic, functions (sqrt, sin, log), comparisons, and constants (pi, e) - safely, in real time. Input is constrained to math-safe characters, fully client-side.
/math-evaluatorMortgage Calculator
Compute monthly payments, the full amortization schedule and total interest, with extra-payment what-if analysis showing months and interest saved — runs entirely in your browser.
/mortgage-calculatorNumber Base Converter
Convert numbers between binary, octal, decimal and hexadecimal. BigInt-powered, so it handles arbitrarily large values without precision loss.
/number-basePercentage Calculator
Calculate percentages three ways - X% of Y, X is what percent of Y, and the percentage change between two values. Runs entirely in your browser, with a shareable link.
/percentage-calculatorPunycode Converter
Convert internationalized domain names (IDN) between Unicode and Punycode (xn--) ACE form. RFC 3492 compliant, runs entirely in your browser, with a shareable link to your exact input.
/punycodeRoman Numeral Converter
Convert integers up to 3,999,999 to Roman numerals and back. Vinculum overline above 3,999, canonical-form validation, a step-by-step greedy breakdown, and 14 language sources. Runs entirely in your browser.
/roman-numeral-converterSubnet / CIDR Calculator
Compute IPv4 subnet details from a CIDR block - network, broadcast, host range, netmask, wildcard, host count, IP class, and private-range detection. Split a block into smaller subnets, all in your browser.
/subnet-cidrXML ↔ JSON Converter
Convert XML to JSON and back, preserving attributes. Validates input and reports errors clearly, runs entirely in your browser, with a shareable link to your exact input.
/xml-to-json
Validators & Testers
9JWT Debugger
newDecode a JSON Web Token and inspect its header and payload as pretty JSON, with exp/iat claim awareness and an expiry badge. Runs entirely in your browser.
/jwtRegex Tester
newTest regular expressions against any text with all flags (g/i/m/s/u/y). See every match, its index and capture groups, plus the constructed pattern. 100% in-browser.
/regex-testerCredit Card Validator
Validate credit card numbers with the Luhn checksum and detect the issuing brand (Visa, Mastercard, Amex, Discover, Diners, JCB, UnionPay, Maestro). 100% client-side - nothing is transmitted.
/credit-card-validatorEmail Validator
Validate email addresses one at a time or in bulk. Checks syntax, length limits, local-part and domain rules, plus-addressing, and IP-literal domains - all in your browser.
/email-validatorIBAN Validator
Validate International Bank Account Numbers (IBAN) with the mod-97 checksum, verify the country-specific length, and format the result. 100% client-side, no network.
/iban-validatorJSON Validator
Validate JSON and pinpoint errors with line and column numbers. Clear valid/invalid verdict plus the exact error location - runs entirely in your browser.
/json-validatorPassword Strength Analyser
Estimate password strength with zxcvbn - realistic dictionary and pattern cracking with crack-time estimates and improvement suggestions. Runs entirely in your browser.
/password-strength-analyserRegex Explainer
Translate a regular expression into plain English, step by step. Explains anchors, character classes, quantifiers, groups, escapes, alternation, and flags.
/regex-explainerSemver Checker
Parse, compare, and validate Semantic Versioning 2.0.0 strings. Check which of two versions is greater (with full prerelease precedence), test whether a version satisfies an npm-style range (^, ~, comparators, hyphen, ||), and bump major/minor/patch/prerelease. Runs 100% client-side.
/semver
Generators
10Password Generator
newGenerate cryptographically-random passwords with a CSPRNG using rejection sampling (no modulo bias). Shows live entropy in bits, a 5-tier strength meter, average offline-GPU crack time, and a Pro mode with the entropy formula, a crack-time-vs-length curve, and a 4-scenario attack table. Everything runs locally - nothing is sent anywhere.
/password-generatorUUID Generator
newGenerate RFC 4122 v4 UUIDs with crypto-grade randomness. Bulk generate, copy all, toggle format (uppercase / no hyphens).
/uuidLorem Ipsum Generator
Generate placeholder Lorem Ipsum text - paragraphs and sentences with adjustable counts. Classic Latin word pool, instant copy.
/lorem-ipsumMAC Address Generator
Generate random EUI-48 MAC addresses with a chosen separator, optional OUI prefix, uppercase formatting, and a locally-administered flag. Runs entirely in your browser with crypto-grade randomness.
/mac-address-generatorMock Data Generator
Generate deterministic fake data (names, emails, numbers, dates, booleans, UUIDs, pick-from-list) from a schema and a seed. Reproducible output.
/mock-data-generatorQR Code Generator
Turn any text or URL into a downloadable QR code. Full ISO encoder with all error-correction levels, versions 1-40, SVG and PNG export, colors and quiet-zone control — runs entirely in your browser.
/qr-code-generatorRandom Port Generator
Generate one or many random TCP/UDP port numbers across registered, ephemeral, or the full range - optionally unique. Runs entirely in your browser with crypto-grade randomness.
/random-port-generatorrobots.txt Generator
Build a standards-compliant robots.txt with per-user-agent allow/disallow rules, crawl-delay, and sitemap entries.
/robots-txt-generatorSecure Token Generator
Generate cryptographically-secure random tokens in your browser. Pick the entropy size and format - hex, base32, base64, base62, or alphanumeric - and see the real strength in bits. Runs entirely client-side.
/token-generatorULID Generator
Generate Universally Unique Lexicographically Sortable Identifiers (ULID) - 26-character Crockford-base32 strings that sort by millisecond timestamp. Paste any ULID to decode its timestamp and randomness. Runs entirely in your browser.
/ulid-generator
Diagnostics
4Browser Support Test
newAudit your real browser against 30 modern web capabilities - WebGPU, WASM, WebAuthn, Service Workers and more. Get a weighted readiness score, copy-paste detection snippets, and a shareable link.
/browser-support-testWHOIS & RDAP Lookup
newLook up registration data for any domain, IP address, or ASN — straight from your browser to the authoritative RDAP registry over HTTPS. No backend, no database of lookups, fully private.
/whoisText Extractor
Pull URLs, emails, IPv4/IPv6 addresses, hashes (MD5/SHA-1/SHA-256/SHA-512), and domains out of logs, headers, or any pasted text.
/extractURL Inspector
Break any URL into its components - protocol, host, port, path, query params, hash, and credentials. Detects default ports and security at a glance, with a decode toggle for query values. Runs entirely in your browser.
/url-inspector
Text & String
10Case Converter
Convert text between UPPER, lower, Title, Sentence, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and slug. Live, one-click copy.
/case-converterDefang / Refang
Make URLs, IPs, and emails safe to paste by defanging indicators (https:// → hxxps[://], . → [.], @ → [@]) - and reverse refanged text back to its original form. Runs entirely in your browser, with a shareable link to your exact input and mode.
/defang-refangFind & Replace
Find and replace text with literal or regular-expression matching, global replace, case sensitivity, whole-word, and capture-group substitution. Live match counter.
/find-replaceHTML Entity Encoder/Decoder
Encode text to HTML entities and decode entities back to text (named + numeric). UTF-8 safe, runs entirely in your browser, with a shareable link to your exact input.
/html-entity-encoderSlugify
Generate clean, URL-safe slugs from any text with locale-aware Unicode transliteration. Accents, emoji, and punctuation are handled automatically - runs entirely in your browser.
/slugifySort Lines & Remove Duplicates
Alphabetize, reverse, shuffle, dedupe, or length-sort lines of text. Supports case-insensitive and natural sorting (file2 before file10).
/sort-linesText Diff Viewer
Compare two pieces of text and see exactly what changed. Highlights added and removed lines, words, or characters, shows a per-side summary, and exports a unified diff you can paste into a PR or commit. Runs 100% in your browser.
/text-diffText Statistics & Readability
Count words, sentences, paragraphs, characters, lines, and reading time, plus Flesch Reading Ease and Flesch-Kincaid grade-level readability scores.
/text-statsUTM Link Builder
Build campaign tracking URLs with utm_source, utm_medium and utm_campaign parameters. Bulk mode processes a whole list, presets and import round-trip existing tracking URLs, and a validator flags attribution-breaking values — runs entirely in your browser.
/utm-link-builderWord & Character Counter
Live word, character, sentence, and paragraph counts plus reading-time estimate as you type.
/word-counter
Color & Design
7Color Contrast Checker
newCheck WCAG 2.2 contrast ratio between any two colors with AA / AAA pass-fail for normal and large text, plus a live preview. For accessible, on-brand design.
/contrastColor Palette Generator
newGenerate harmonious color palettes - complementary, analogous, triadic, tetradic, and monochromatic - from any base color. Export to CSS, Tailwind, or JSON.
/palette-generatorCSS Animation Playground
newDesign and test CSS animations live - preview easing curves, durations, and keyframes, then copy the exact CSS.
/css-animation-playgroundBox-Shadow Generator
Design layered CSS box-shadows with offset, blur, spread, color, and inset. Live preview and copy-ready CSS.
/box-shadow-generatorColor Picker & Converter
Pick a color and convert between HEX, RGB, HSL, HSV, and CMYK with a live preview. Edit any format and copy the rest - runs entirely in your browser.
/color-pickerCSS Gradient Generator
Build linear, radial, and conic CSS gradients with multiple color stops and positions. Live preview and copy-ready CSS.
/css-gradient-generatorGlassmorphism Generator
Create frosted-glass CSS - backdrop-blur, translucent background, subtle border, and soft shadow - with a copy-ready snippet and live preview.
/glassmorphism-generator
Privacy & Security
34Password Generator
newGenerate cryptographically-random passwords with a CSPRNG using rejection sampling (no modulo bias). Shows live entropy in bits, a 5-tier strength meter, average offline-GPU crack time, and a Pro mode with the entropy formula, a crack-time-vs-length curve, and a 4-scenario attack table. Everything runs locally - nothing is sent anywhere.
/password-generatorAge File Encryption
Encrypt and decrypt files with age — a modern, simple alternative to PGP. Password-based encryption runs entirely in your browser.
/age-encryptionArgon2 Hash & Verify
Hash passwords with Argon2id — the winner of the Password Hashing Competition. Configure memory, iterations, and parallelism. WASM-powered, client-side.
/argon2Bcrypt Hash & Verify
Hash a password with bcrypt or verify a password against an existing bcrypt hash. Configurable cost factor. Runs entirely in your browser.
/bcryptBrowser Fingerprint Viewer
See exactly what websites can learn about your browser without cookies — screen, GPU, fonts, timezone, language, and more. Educational, not tracking.
/browser-fingerprintCertificate Decoder
Paste a PEM X.509 certificate and see its subject, issuer, SAN, validity, key usage, fingerprints, and chain details in a human-readable format.
/cert-decoderChecksum Verifier
Drag and drop a file to compute its MD5, SHA-1, SHA-256, and SHA-512 checksums. Paste an expected hash to verify integrity - detect tampered or corrupted downloads instantly. Runs entirely in your browser.
/checksum-verifierCSP Builder
Build a Content-Security-Policy header interactively. Toggle directives, add sources, see the assembled header in real time — with a security score that flags unsafe sources.
/csp-builderCSR Generator
Generate a Certificate Signing Request and private key pair entirely in your browser. Download the CSR and key as PEM files.
/csr-generatorDefang / Refang
Make URLs, IPs, and emails safe to paste by defanging indicators (https:// → hxxps[://], . → [.], @ → [@]) - and reverse refanged text back to its original form. Runs entirely in your browser, with a shareable link to your exact input and mode.
/defang-refangDigital Signature
Sign messages with Ed25519 or ECDSA and verify signatures. Prove authorship without revealing your private key.
/digital-signatureDKIM / SPF / DMARC Builder & Checker
Build the three email-authentication DNS records — SPF, DKIM, and DMARC — as ready-to-paste TXT values, or look up a domain's live records over DNS-over-HTTPS. Import existing records, catch publishing mistakes, share via URL. Entirely client-side.
/dkim-spf-dmarcEmail Header Analyzer
Paste raw email headers to trace the message path, detect spoofing, and check SPF/DKIM/DMARC authentication results. Runs entirely in your browser.
/email-header-analyzerEntropy Visualizer
Visualize the randomness quality of any data. See Shannon entropy, byte frequency distribution, chi-squared score, and a visual entropy heatmap.
/entropy-visualizerEXIF & Metadata Stripper
View and strip GPS, camera, date, and software metadata from photos entirely in your browser. Download a clean copy.
/exif-stripperFile Encryptor
Encrypt or decrypt any file with AES-256-GCM in your browser. Password-based, zero server contact. Drag, drop, done.
/file-encryptorHash Generator
Compute SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text at once, using the browser's native SubtleCrypto. Copy each digest. 100% client-side.
/hashHMAC Generator
Generate a keyed-hash HMAC (SHA-1/256/384/512) for a message and secret. Runs entirely in your browser via Web Crypto, with a shareable link to your exact input.
/hmac-generatorImage Steganography
Hide a secret message inside a PNG image or extract a hidden message from one. Uses least-significant-bit encoding with optional AES encryption.
/steganographyOTP Code Generator
Generate time-based one-time passwords (RFC 6238 TOTP) from a Base32 secret, with selectable algorithm, digit count, and period - updating live, entirely in your browser.
/otp-code-generatorPassphrase Generator
Generate memorable, high-entropy passphrases from the EFF diceware wordlist using cryptographic randomness. Each word is drawn with crypto.getRandomValues and rejection sampling (no modulo bias), and every passphrase shows its exact entropy in bits plus the estimated crack time at 1 trillion guesses/sec. Everything runs locally - nothing is sent anywhere.
/passphrase-generatorPassword Breach Checker
Check if a password has appeared in known data breaches using k-anonymity. Only the first 5 characters of the SHA-1 hash are sent - your full password never leaves your browser.
/breach-checkerPassword Strength Analyser
Estimate password strength with zxcvbn - realistic dictionary and pattern cracking with crack-time estimates and improvement suggestions. Runs entirely in your browser.
/password-strength-analyserPermissions-Policy Builder
Build a Permissions-Policy header interactively. Control which browser features (camera, microphone, geolocation, etc.) your site can use.
/permissions-policyPGP Encrypt & Decrypt
Encrypt or decrypt messages with PGP public/private keys. Powered by OpenPGP.js, runs entirely in your browser.
/pgp-encryptPGP Key Generator
Generate PGP key pairs (ECC or RSA) in your browser. Download your public and private keys. Powered by OpenPGP.js.
/pgp-keygenPII Redactor
Paste text and automatically detect and mask personal data — emails, phone numbers, IP addresses, SSNs, credit card numbers, and dates.
/pii-redactorPrivacy Score
One number for your privacy health: your browser fingerprint, a test password's strength and breach exposure, and a site's security headers — four checks, one score, concrete fixes. Runs in your browser; only a 5-character hash prefix ever leaves it.
/privacy-scoreSecure Token Generator
Generate cryptographically-secure random tokens in your browser. Pick the entropy size and format - hex, base32, base64, base62, or alphanumeric - and see the real strength in bits. Runs entirely client-side.
/token-generatorSecurity Headers Analyzer
Paste HTTP response headers to analyze security posture. Checks CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy.
/security-headersShamir's Secret Sharing
Split a secret into N shares where any K shares can reconstruct it — but fewer than K reveal nothing. Based on Shamir's threshold scheme over GF(256).
/secret-sharingSSH Key Generator
Generate Ed25519 or RSA SSH key pairs in your browser. Copy or download the public and private keys. No server involved.
/ssh-keygenText Encryptor
Encrypt or decrypt text with a password using AES-256-GCM. Share the ciphertext safely - only someone with the password can read it.
/text-encryptorWireGuard Key Generator
Generate Curve25519 key pairs for WireGuard VPN configuration. Derives the public key from a clamped private key with a pure-BigInt RFC 7748 Montgomery ladder, optionally generates a pre-shared key, and renders a ready-to-edit wg-quick config template. Everything runs 100% client-side - keys never leave your browser.
/wireguard-keygen
Data & DevOps
14SQL Playground
newRun real SQL on sample datasets - or your own schema - right in the browser. Write queries, see formatted results instantly, and export or share them. Powered by sql.js (SQLite WASM); 100% client-side.
/sql-playgroundASCII Table
A searchable, filterable reference for all 128 ASCII code points. See the decimal, hex, octal, and binary form of every character, narrow to printable characters only, clamp the code-point range, and click any row to copy. Runs 100% client-side.
/ascii-tableBitwise Calculator
Perform AND, OR, XOR, NOT, shifts and rotates on 8/16/32/64-bit values with exact bigint math. Enter operands in binary, octal, decimal or hex and read the result in every base plus a live bit grid. Runs 100% in your browser.
/bitwisechmod Calculator
Compute Unix file permissions between octal (e.g. 755), symbolic (rwxr-xr-x), and decimal - including setuid, setgid, and sticky bits. Toggle permissions interactively, fully client-side, with a shareable link.
/chmod-calculatorCron Expression Explainer
Translate any 5-field cron expression into plain English, build one field-by-field, and preview the next time it will fire. Supports steps, ranges, lists, and named days/months. Runs 100% in your browser.
/cron-explainerCSV to SQL Importer
Turn CSV data into SQL import statements: batched multi-row INSERTs, a Postgres COPY FROM STDIN block, or a MySQL LOAD DATA statement. Infers numeric columns, emits NULL for empty fields, sanitizes and de-duplicates header names into SQL identifiers.
/csv-to-sqlER/Schema Visualizer
Paste CREATE TABLE DDL and get an ER diagram as SVG: tables with typed columns, primary keys, and foreign-key arrows in a deterministic layered layout. Pan and zoom the live diagram; export the SVG.
/schema-visualizerHTTP Methods Reference
A searchable reference for every HTTP request method - GET, POST, PUT, PATCH, DELETE, and more. See at a glance which are safe, idempotent, and cacheable, then compare any two methods side by side.
/http-methodsHTTP Status Codes
Searchable reference of all HTTP status codes with meaning, category, and usage notes.
/http-status-codesJSON to SQL INSERT
Convert a JSON array of objects into SQL INSERT statements. Properly escapes strings, handles nulls, booleans, numbers, nested objects, and multi-row inserts.
/json-to-sqlJSON-RPC Request Builder
Build valid JSON-RPC 2.0 requests, notifications, success responses, and error responses, plus batch arrays. Validate message structure.
/json-rpc-builderMIME Type Reference
A searchable map of common file extensions to their MIME types - text, image, audio, video, application, font, and multipart. Look up by extension or by type, filter by category, and copy the exact Content-Type string for any format.
/mime-typesStatistics Calculator
Compute descriptive statistics - count, sum, mean, median, mode, min/max, range, variance, standard deviation, and quartiles (Q1/Q3/IQR) - from any list of numbers. Tolerates mixed separators and flags unparseable tokens. Choose sample (n−1) or population (n) variance. Everything runs 100% client-side.
/statisticsTimestamp Converter
Convert Unix epoch timestamps to human-readable dates and back. See seconds, milliseconds, ISO 8601, UTC, local and relative time at once.
/timestamp
Images & Media
10App Icon Generator
Turn one image into the full web app icon set — favicon, apple-touch-icon and manifest sizes as crisp PNGs. Letterboxed contain-fit, optional white background — runs entirely in your browser.
/app-icon-generatorGIF Frame Extractor
Split an animated GIF into PNG frames with per-frame delays — decoded by our own pure GIF parser, entirely in your browser. Nothing uploads.
/gif-frame-extractorImage Compressor
Shrink image file sizes entirely in your browser — fixed quality or an automatic fit to a size budget, optional max-dimension resize, batch support. Nothing uploads.
/image-compressorImage Converter
Convert images between PNG, JPEG and WebP entirely in your browser. Batch-friendly with quality control and a before/after size delta — nothing is uploaded.
/image-converterImage Resize & Watermark
Batch-resize images by width, height or percentage and stamp a text watermark with position, opacity and size control — entirely in your browser, nothing uploaded.
/image-resize-and-watermarkImage Splitter
Split an image into an even grid of tiles — rows × columns with a live cut-line preview and per-tile or bulk PNG download. Runs entirely in your browser.
/image-splitterMedia Metadata Inspector
Inspect audio, video and image files at the byte level — MP4 boxes, ID3 tags, WAV chunks, GIF headers — parsed by our own readers, entirely in your browser.
/media-metadata-inspectorPalette from Image
Extract the dominant colors from any image as a reusable palette — median-cut quantization with population shares, hex and rgb, copyable — runs entirely in your browser.
/palette-from-imagePhoto Merge
Combine photos side by side, stacked, or in a grid — uniform cells, adjustable gap, one PNG out. Runs entirely in your browser.
/photo-mergeVideo to GIF Converter
Convert a video clip to an animated GIF — frame capture, palette quantization and GIF encoding all run locally with our own encoder. Nothing uploads.
/video-to-gif