Free online developer tools

Decode and inspect JWTs in your browser. Header, payload, and signature. Optional local verify if you paste a key. The token is not sent anywhere.

Turn a cron expression into plain English and upcoming run times. Runs in the browser.

Generate strong passwords with the Web Crypto API in your browser. Nothing is sent or stored on a server.

Calculate SHA-256 checksums of files or text with Web Crypto in your browser. No file uploading.

Generate version 4 UUIDs with browser cryptographic randomness. Generation is local.

Test JavaScript regular expressions against text in your browser. Patterns and samples stay local.

Convert ASCII text to 8-bit binary instantly in your browser. No upload, no account, no AI. Clean spaced or compact output.

Decode 8-bit binary code into readable ASCII text. 100% client-side, no upload, free. Handles spaced or continuous binary.

Encode or decode URL strings and query parameters in your browser. Your data never leaves your device. Free and private.

Encode text to Base64 or decode Base64 to text in your browser. Your data never leaves your device. Free and private.

Generate BLAKE3 hashes (text or file) with keyed & derive-key modes. 100% browser-based, no upload, no AI. Free & private.

Generate SHA-3-224, SHA-3-256, SHA-3-384 or SHA-3-512 hashes. Client-side only, no upload.

Hash any file with SHA-224/256/512, SHA-3, BLAKE3, CRC32 and more. 100% client-side. Files never leave your browser.

Convert between metric and imperial units instantly. Private, accurate, free.

Filter huge Android Logcat files instantly in your browser. 100% private, no-upload processing with zero server latency.

Mix ambient noise and binaural focus tones locally. 100% private, no-upload audio with zero server latency.

Validate .env syntax and duplicate keys locally. 100% private, no-upload processing with zero server latency.

Visualize cron schedules on a calendar grid locally. 100% private, no-upload processing with zero server latency.

Clean API tokens, Authorization headers and cookies locally. 100% private, no-upload processing with zero server latency.

SHA-256 hash inline scripts for CSP, or mint a cryptographically random nonce. Web Crypto in this tab.

Create a code_verifier and S256 code_challenge with Web Crypto. Nothing is sent to an auth server from this page.

Build linear or radial CSS gradients. Copy the background-image. Preview in this tab.

Decode and inspect JWTs in your browser. Header, payload, and signature. Optional local verify if you paste a key. The token is not sent anywhere.

Turn a cron expression into plain English and upcoming run times. Runs in the browser.

Unix epoch to human date in either direction. Instant, in-page.

Inspect a text log in the browser: search, filter, simple stats. Log contents stay on the device.

Generate strong passwords with the Web Crypto API in your browser. Nothing is sent or stored on a server.

Hash text with bcrypt in your browser. Work runs locally. The plaintext is not sent to a server.

Compute MD5 checksums of text or files in your browser. MD5 is a legacy digest, not a password hash. Nothing is uploaded.

Calculate SHA-256 checksums of files or text with Web Crypto in your browser. No file uploading.

Generate Subresource Integrity hashes from pasted source or a local file using SHA-256, SHA-384, or SHA-512 in the browser.

Encode or decode Base32 (RFC 4648) in your browser. Text stays in this tab.

Convert hexadecimal to ASCII text in your browser. No data is uploaded.

Convert text to hexadecimal in your browser. Encoding is local.

Generate version 4 UUIDs with browser cryptographic randomness. Generation is local.

Test JavaScript regular expressions against text in your browser. Patterns and samples stay local.

Parse a user-agent string in your browser — yours or a pasted one. No fingerprinting service is called.

Format SQL in your browser with tokenized parsing. Queries are not sent to a server.

Convert ASCII text to 8-bit binary instantly in your browser. No upload, no account, no AI. Clean spaced or compact output.

Decode 8-bit binary code into readable ASCII text. 100% client-side, no upload, free. Handles spaced or continuous binary.

Free Hz music generator and online tone generator. Play any frequency from 20 Hz to 20 kHz — sine, square, triangle, sawtooth. 440 Hz, 432 Hz, 1 kHz test tones. 100% client-side.

Build a valid sitemap.xml with changefreq, priority, and lastmod. Paste URLs, set values, download. 100% client-side, no upload.

Encode or decode URL strings and query parameters in your browser. Your data never leaves your device. Free and private.

Encode text to Base64 or decode Base64 to text in your browser. Your data never leaves your device. Free and private.

Compute HMAC (SHA-256 etc.) signatures in your browser. Your data never leaves your device. Free and private.

Generate SHA-1 hashes of text or files in your browser. Your data never leaves your device. Free and private.

Generate a SHA-384 hash of text or a file in your browser. Data never leaves your device. Free, private, no upload.

Generate SHA-512 hashes in your browser. Your data never leaves your device. Free and private.

Parse URL query strings into key/value pairs in your browser. Your data never leaves your device. Free and private.

Parse a full URL into protocol, host, path, query and hash in your browser. Your data never leaves your device. Free and private.

Test JSONPath expressions against JSON in your browser. Your data never leaves your device. Free and private.

Generate TypeScript interfaces from JSON objects in your browser. Your data never leaves your device. Free and private.

Beautify and indent HTML code in your browser. Your code never leaves your device. Free and private.

Minify CSS code by removing whitespace in your browser. Your code never leaves your device. Free and private.

Convert numbers between binary, octal, decimal and hex in your browser. Your data never leaves your device. Free and private.

Encode text to Morse code or decode Morse back to text in your browser. Your data never leaves your device. Free and private.

Generate a QR code image from text or URL in your browser. Your data never leaves your device. Free and private.

Check password length and character classes in your browser. The password is never sent anywhere. Free and private.

Generate BLAKE3 hashes (text or file) with keyed & derive-key modes. 100% browser-based, no upload, no AI. Free & private.

Calculate CRC-32 (IEEE, Castagnoli, BZIP2, etc.) for text or files in your browser. Never uploaded. Free forever.

Generate CRC-64 checksums (ECMA-182 and variants) for text or files. 100% client-side, no upload.

Compute Adler-32 checksums used by zlib and PNG. Browser-only, no upload.

Generate SHA-224 hashes for text or files. 100% browser-based, no upload, free.

Generate SHA-3-224, SHA-3-256, SHA-3-384 or SHA-3-512 hashes. Client-side only, no upload.

Compute raw Keccak hashes (including Ethereum’s keccak-256). 100% client-side, private.

Generate RIPEMD-160 hashes used in Bitcoin addresses. Client-side, no upload.

Generate and verify Argon2id/i/d password hashes with full memory/time/parallelism control. 100% browser-based.

Generate scrypt hashes and derived keys with custom N/r/p parameters. Client-side only.

Derive keys with PBKDF2-HMAC-SHA256/512. Configurable iterations & length. 100% client-side.

Hash any file with SHA-224/256/512, SHA-3, BLAKE3, CRC32 and more. 100% client-side. Files never leave your browser.

Encode or decode Base58 (Bitcoin alphabet) for text or hex. 100% client-side, private.

Encode/decode Base62 for compact alphanumeric strings. Browser-only, no upload.

Encode or decode Base85 (Ascii85) data. 100% client-side and private.

Convert text to binary and binary back to text. Free, private, client-side.

Encode text or data to Base32 (RFC 4648). 100% client-side, free.

Convert any file (image, PDF, etc.) to Base64 in your browser. Never uploaded. Free.

Paste Base64 and download the original file (image, PDF, etc.). 100% private, client-side.

Bundle files into a ZIP archive in your browser. No upload, no size limits beyond device memory.

Open and extract ZIP archives in your browser. Preview contents, download selectively. No upload.

BETA. Trim video to WebM in your browser. No upload. MP4 (H.264) and WebM work best; many screen recordings will not decode.

Edit audio (trim, convert, merge, volume) in your browser. No upload required.

Test your microphone volume and input instantly. No upload, no account, private.

Test your webcam or camera feed instantly. No recording stored, no upload.

Scan QR codes using your camera or by uploading an image. 100% client-side, private.

Create scannable barcodes (UPC-A, EAN-13, Code 128, Code 39…). Download PNG/SVG. Private, free.

Scan 1D barcodes (UPC, EAN, Code 128…) with your camera or from an image. Private, client-side.

Full scientific calculator with trig, logs, powers, constants. Runs in your browser, no account.

Convert between metric and imperial units instantly. Private, accurate, free.

Convert times across time zones instantly. See multiple cities at once. Private, free.

Calculate exact age in years, months, days. Free, private, instant.

Simple countdown timer or stopwatch. Custom times, browser notifications. Private, no account.

Create and manage tasks that stay only in your browser. No account, no cloud sync required.

Filter huge Android Logcat files instantly in your browser. 100% private, no-upload processing with zero server latency.

Mix ambient noise and binaural focus tones locally. 100% private, no-upload audio with zero server latency.

Validate .env syntax and duplicate keys locally. 100% private, no-upload processing with zero server latency.

Visualize cron schedules on a calendar grid locally. 100% private, no-upload processing with zero server latency.

Clean API tokens, Authorization headers and cookies locally. 100% private, no-upload processing with zero server latency.

SHA-256 hash inline scripts for CSP, or mint a cryptographically random nonce. Web Crypto in this tab.

Parse a Content-Security-Policy header. Flag unsafe-inline, wildcards, and missing object-src. Local parse.

Emit CSP, COOP, COEP, Referrer-Policy, HSTS, and X-Content-Type-Options snippets from checkboxes.

Build a Permissions-Policy / Feature-Policy header for camera, mic, geolocation, and payment.

Create a code_verifier and S256 code_challenge with Web Crypto. Nothing is sent to an auth server from this page.

Build HS256 JWTs in the browser with Web Crypto. Header, payload, HMAC. Keys never leave the tab.

Generate RFC 6238 TOTP codes from a Base32 secret. Clock is your device. Nothing is synced.

Simulate an OPTIONS preflight from origin, method, and request headers. No network call.

Compose iframe sandbox tokens and Cross-Origin-Opener/Embedder-Policy headers. Copy attributes.

Create a local RTCPeerConnection and list ICE candidate IPs. No STUN server you do not choose. Nothing is posted.

Pick dest, mode, site, and user to see Sec-Fetch-* request headers a browser would send.

Build linear or radial CSS gradients. Copy the background-image. Preview in this tab.

Layer CSS box-shadows with offset, blur, spread, and color. Copy the declaration.

Toggle flex-direction, wrap, justify-content, and align-items on a live preview. Copy CSS.

Set columns, rows, and gap. Preview grid-template. Copy CSS.

Build polygon() clip-path from a few presets or point list. Copy CSS.

Paste SVG. Strip comments, editor junk, and extra whitespace. Download a smaller SVG.

Parse viewBox and width/height. Suggest a tighter viewBox from numeric path bounds when possible.

Emit a modern visually-hidden / sr-only CSS snippet and a sample span.

Tick WCAG 2.2 AA criteria. Download a markdown report. State stays in this tab.

Pick time zones and working hours. See overlapping UTC windows. No calendar sync.

Paste web app manifest JSON. Check name, icons, display, and start_url. Installability heuristics only.

Generate an ECDSA P-256 VAPID public/private key pair with Web Crypto. Keys stay in this tab.

Parse Cookie or Set-Cookie strings. Flag missing Secure/HttpOnly/SameSite and oversize values.