Free Online Developer Tools
JSON, encodings, timestamps, UUIDs, hashes — everyday developer utilities that run locally, so sensitive data never leaves your browser.
JSON Formatter
Beautify, minify & validate JSON with line-precise errors
Open tool →Hash Calculator
MD5, SHA-1/256/384/512 computed live, one-click copy
Open tool →Base64 Encode/Decode
UTF-8 safe Base64 encoding & decoding with URL-safe output
Open tool →URL Encode/Decode
encodeURIComponent / encodeURI modes with live two-way sync
Open tool →Timestamp Converter
Convert Unix timestamps to dates and back, seconds or milliseconds
Open tool →UUID Generator
Bulk-generate v4 UUIDs with uppercase and no-hyphen options
Open tool →HTML Entity Encode/Decode
Two-way HTML entity conversion: named, decimal and hexadecimal entities
Open tool →AES Encrypt/Decrypt
WebCrypto AES-GCM-256 passphrase encryption in a single Base64 string
Open tool →RSA Keys & Encryption
Generate an RSA-2048 keypair, encrypt with the public key, decrypt with the private
Open tool →Cron Parser
Interpret 5-field cron expressions: plain-language description + next 5 runs
Open tool →Cron Generator
Build 5-field cron expressions visually, with a next-5-runs preview
Open tool →Timezone Converter
Convert times across time zones, with UTC / New York / London / Tokyo reference
Open tool →JSON to XML
Convert JSON objects/arrays to XML with a configurable root
Open tool →JSON to YAML
YAML serialization with 2-space indent and spec-aware quoting
Open tool →JSON to CSV
Object arrays to CSV with RFC 4180 escaping and BOM download
Open tool →XML Formatter
Parse & pretty-print XML, minify to one line, precise errors
Open tool →XML to JSON
Attributes under @attributes, repeated elements as arrays
Open tool →Why these developer tools?
Local first
Parsing, encoding and hashing all happen in your browser — API payloads and keys are never uploaded.
Instant, zero setup
Pure static pages: no sign-up, no install, and they load fast even on flaky connections.
Debuggable output
JSON errors point to the exact line and column; every encode/decode is reversible and copy-ready.