Dev Toolboxclient-side utilities
✦ privacy-first developer utilities

Every dev tool you reach for, running entirely in your browser.

No uploads, no tracking, no backend. Format, convert, generate and inspect — your data never leaves this tab. Pick a tool to begin.

Converters
Image Converter
PNG · WebP · JPEG · AVIF via Canvas
JSON ↔ YAML ↔ CSV
Convert between structured data formats
Base64
Encode / decode text, files & images
Markdown ↔ HTML
Render Markdown or convert HTML back
Color Converter
HEX · RGB · HSL · OKLCH with live preview
Timestamp
Unix epoch ↔ human date & relative time
JSON & String
JSON Formatter
Format, validate & explore as a tree
Diff Viewer
Side-by-side text & JSON comparison
Regex Tester
Test patterns with live match highlight
Case Converter
camelCase, snake_case, kebab, Pascal
URL Encode / Parse
Encode/decode & inspect query strings
SQL Formatter
Pretty-print and indent SQL queries
ENV ↔ JSON
Convert .env files to JSON and back
Generators
Hash Generator
MD5 · SHA-1 · SHA-256 · SHA-512
UUID / nanoid
Generate IDs in bulk with options
QR Code
Text → QR with embedded logo & layout
JWT Decoder
Decode header, payload & expiry
Cron Parser
Explain cron & show next run times
AI Prompt Tools
Token Counter
Count tokens & estimate model cost
Prompt Templates
Reusable {{variables}} saved locally
Prompt Cleaner
Strip zero-width chars & normalize
MD ↔ XML Prompt
Structure prompts with <context> tags
Context Window
Visualize usage vs model window
Utilities
Keep Screen Awake
Screen Wake Lock with optional timer
Pomodoro / Stopwatch
Focus timer and stopwatch