SweetLemon Lab
Free developer, AI, and productivity tools that run entirely in your browser. No signup, no tracking, no nonsense.
Unit Converter
Convert between units of length, weight, area, volume, temperature, and speed — instant, offline, no signup.
Time
Convert timestamps, durations, timezones, date diffs, and calendars — all in one place.
Markdown Editor
Write and preview Markdown with a live three-pane editor — no signup, no server, runs entirely in the browser.
QR Code Generator
Generate QR codes for URLs, text, and contact info instantly.
coming soonUUID / Hash / Base64
Generate UUIDs, compute hashes, and encode or decode Base64 strings.
coming soonJSON Formatter
Format, validate, and minify JSON with syntax highlighting.
coming soonJWT Decoder
Decode and inspect JSON Web Tokens without sending them to a server.
coming soonRegex Tester
Test regular expressions against sample text with live match highlighting.
coming soonText Diff
Compare two blocks of text and see additions, deletions, and changes.
coming soonTokenizer
Visualize how text is split into tokens for popular LLM models.
coming soonAI Cost Calculator
Estimate API costs for OpenAI, Anthropic, and other LLM providers.
coming soonClaude Code Cost
Track and estimate costs for Claude Code sessions and token usage.
coming soon