Free online developer tools
Fast, privacy-first utilities for everyday development — format JSON, convert Base64 and URLs, decode JWTs, and generate hashes and UUIDs. Everything runs entirely on your device — nothing leaves your browser.
JSON & data
JSON Formatter & Parser
Beautify, minify, and validate JSON with syntax highlighting, bracket matching, and instant error checking.
Open tool →JSON Unescape & Escape
Turn escaped JSON strings back into readable text, or escape text for embedding in JSON — with optional deep unescape.
Open tool →JSON ↔ CSV Converter
Convert a JSON array of objects to CSV, or parse CSV back into JSON — with proper quoted-field and newline handling.
Open tool →JSON ↔ YAML Converter
Turn JSON into clean, readable YAML, or parse YAML back into JSON — comments, block scalars, and validation included.
Open tool →Diff Checker
Compare two texts or code snippets line by line and see the differences as a unified diff, with ignore-whitespace and ignore-case.
Open tool →Encoding
Cryptography
JWT Decoder & Encoder
Decode, verify, and sign JSON Web Tokens locally with real HS/RS/PS/ES signature checks via the Web Crypto API.
Open tool →Hash Generator
Compute MD5, SHA-1/256/384/512, SHA-3, Keccak-256, or CRC32 for any text or file — drag and drop to get a checksum.
Open tool →HMAC Generator
Compute HMAC-SHA256, SHA-1, SHA-384, or SHA-512 signatures for a message and secret key via the Web Crypto API.
Open tool →Generators & converters
UUID Generator
Generate random v4, sortable v7, or timestamp v1 UUIDs in bulk, with your choice of separator. Cryptographically random.
Open tool →Unix Timestamp Converter
Convert an epoch timestamp to a date in UTC and local time, or a date back to a Unix timestamp. Seconds or milliseconds.
Open tool →Date & Time Now
The current date and time right now — live Unix timestamp, ISO 8601, UTC, and local formats, one click to copy.
Open tool →QR Code Generator
Turn any text or URL into a QR code, tune the error-correction level and size, and download it as SVG or PNG.
Open tool →