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Developer Tools

Twenty-four single-page browser tools that run entirely on your machine. No analytics on these pages, no requests to a backend on submit, no telemetry. Bookmark them, use them offline, paste them in incognito tabs. Every tool below loads in under 200ms and respects your time. Full index also at /tools.

Encoders & Decoders
Base64
Encode and decode strings or files. Round-trip safe, supports binary upload, copy with one click.
EncodingFiles
Hex Converter
Two-way between bytes, integers, ASCII, and color hex. Useful for debugging binary protocols and CSS.
EncodingColor
URL Encoder
Percent-encode and decode query strings, paths, and fragments. Handles unicode, plus-vs-space variants.
WebEncoding
HTML Entities
Encode and decode & < > and 250+ named/numeric entities. For XSS-safe output and email templates.
WebEncoding
JWT Decoder
Decode JWTs, inspect header/payload/signature, check expiry. Decoder runs locally, never leaves your browser.
AuthSecurity
Data Formats
JSON Formatter
Pretty-print, validate, collapse, jq-style queries. Handles 50MB inputs without hanging.
DataValidation
YAML Converter
YAML to JSON and back, validation, syntax highlight. Catches indent errors and tab/space mixes.
DataConfig
Markdown Preview
Live render, GitHub-flavored, copy HTML output. Tables, fenced code, task lists all supported.
WebWriting
Generators
UUID Generator
v1, v4, v7, batch mode. Lowercase or upper, with or without hyphens. Bulk export to CSV.
GeneratorDatabase
Password Generator
Length, charset, entropy meter, copy. Generated client-side, never transmitted.
SecurityGenerator
Hash Generator
MD5, SHA-1, SHA-256, SHA-512. For checksums, integrity verification, and quick fingerprinting.
SecurityGenerator
Lorem Ipsum
Words, sentences, paragraphs at custom length. Plus a "hacker ipsum" mode for prototype copy.
GeneratorDesign
QR Generator
Text, URL, contact card, downloadable PNG/SVG. All sizes, error correction levels, no watermark.
GeneratorMobile
Time, Date & Pattern Matching
Unix Timestamp
Convert seconds, milliseconds, ISO 8601 across timezones. Live clock for sanity-checking servers.
TimeConversion
Cron Decoder
Parse expressions, show next 10 fire times in your timezone. Handles step values, ranges, lists.
DevOpsScheduling
Regex Tester
Live match, capture groups, common patterns library. Saves the last 10 patterns to localStorage.
PatternValidation
Diff Viewer
Side-by-side or unified, line and char diff. Useful for config audits and copy-paste comparisons.
ComparisonPattern
Network & HTTP
API Tester
Mini Postman, GET, POST, PUT, DELETE, custom headers, JSON body. Saves history locally.
HTTPTesting
HTTP Status Codes
Every status code with explanation, common causes, RFC link. Includes 418 (teapot) and 451 (legal).
HTTPReference
Common Ports
Service-to-port reference, well-known and registered. Quick lookup for firewall and load-balancer config.
NetworkReference
System & Web
Chmod Calculator
Symbolic and numeric Unix permissions. Click bits to compose, paste a mode to decompose.
UnixPermissions
Color Converter
HEX, RGB, HSL, CSS variables, palettes. Eyedropper for the screen, contrast ratio for accessibility.
DesignWeb
Crypto Converters
Gwei Converter
Wei, Gwei, Ether, gas-cost calculator. Live ETH price for USD conversion.
CryptoEthereum
Satoshi Converter
Sats, BTC, USD live conversion. Useful for invoices, micropayments, and Lightning channels.
CryptoBitcoin