Free online developer tools
Small developer utilities that run with Web Crypto and in-page parsers. No account. No upload API.
Popular
JWT inspector
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.
Cron expression explainer
Turn a cron expression into plain English and upcoming run times. Runs in the browser.
Secure password generator
Generate strong passwords with the Web Crypto API in your browser. Nothing is sent or stored on a server.
SHA256 checksum
Calculate SHA-256 checksums of files or text with Web Crypto in your browser. No file uploading.
UUID generator
Generate version 4 UUIDs with browser cryptographic randomness. Generation is local.
Regex tester
Test JavaScript regular expressions against text in your browser. Patterns and samples stay local.
All developer tools
JWT inspector
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.
Cron expression explainer
Turn a cron expression into plain English and upcoming run times. Runs in the browser.
Unix timestamp converter
Unix epoch ↔ human date in either direction. Instant, in-page.
Log file analyzer
Inspect a text log in the browser: search, filter, simple stats. Log contents stay on the device.
Secure password generator
Generate strong passwords with the Web Crypto API in your browser. Nothing is sent or stored on a server.
Bcrypt generator
Hash text with bcrypt in your browser. Work runs locally. The plaintext is not sent to a server.
MD5 hash generator
Compute MD5 checksums of text or files in your browser. MD5 is a legacy digest, not a password hash. Nothing is uploaded.
SHA256 checksum
Calculate SHA-256 checksums of files or text with Web Crypto in your browser. No file uploading.
SRI hash generator
Generate Subresource Integrity hashes from pasted source or a local file using SHA-256, SHA-384, or SHA-512 in the browser.
Base32 encoder / decoder
Encode or decode Base32 (RFC 4648) in your browser. Text stays in this tab.
Hex to ASCII
Convert hexadecimal to ASCII text in your browser. No data is uploaded.
ASCII to hex
Convert text to hexadecimal in your browser. Encoding is local.
UUID generator
Generate version 4 UUIDs with browser cryptographic randomness. Generation is local.
Regex tester
Test JavaScript regular expressions against text in your browser. Patterns and samples stay local.
User agent parser
Parse a user-agent string in your browser — yours or a pasted one. No fingerprinting service is called.
SQL formatter
Format SQL in your browser with tokenized parsing. Queries are not sent to a server.
Why client-side developer tools?
JWTs, checksums, and SQL often include secrets. These pages do not phone home with the payload.