Free tools for AI builders
A growing set of fast, focused tools you can use without an account. All processing happens in your browser.
Token Calculator
Estimate token counts and LLM cost for GPT, Claude, and Gemini prompts.
JSON Formatter
Format, validate, and minify JSON with syntax highlighting.
Prompt Optimizer
Rewrite a prompt using battle-tested structural rules.
Regex Tester
Test regular expressions against sample input with live match highlighting.
UUID Generator
Generate v4 UUIDs one at a time or in bulk.
Base64 Encoder / Decoder
Encode and decode Base64 with UTF-8 support.
Timestamp Converter
Convert between Unix timestamps and human-readable dates in any timezone.
Markdown Formatter & Previewer
Preview Markdown as HTML with a clean live renderer — perfect for LLM output.
JSON Validator
Validate JSON with line-accurate error messages.
Case Converter
Convert text between camelCase, snake_case, kebab-case, and 6 more styles.
URL Slug Generator
Turn titles into clean, SEO-friendly URL slugs.
Word & Character Counter
Count words, characters, sentences, and paragraphs with reading and speaking time.
URL Encoder / Decoder
Encode and decode URLs with encodeURI vs encodeURIComponent options.
Cron Expression Generator
Build and explain cron expressions with presets and a live human-readable description.
Text Diff Checker
Compare two texts line-by-line with additions and removals highlighted.
Password Generator
Cryptographically secure passwords using the Web Crypto API.
CSV to JSON Converter
Convert CSV data to JSON with header detection, quoted fields, and custom delimiters.
JWT Decoder
Inspect JWT header and payload with expiry checks. Signature is not verified.
Color Converter (HEX / RGB / HSL)
Convert between HEX, RGB, and HSL with a live preview.
Lorem Ipsum Generator
Generate placeholder text — paragraphs, sentences, or words — for design mocks.
HTML Entity Encoder / Decoder
Encode or decode HTML entities (&, <, ', etc.).
Hash Generator (SHA-1/256/384/512)
Compute cryptographic hashes in the browser using Web Crypto.
YAML to JSON Converter
Convert hand-written YAML (Kubernetes, GitHub Actions, docker-compose) to JSON.
Markdown Preview
Live-preview Markdown as HTML with copy for both.
Readability Scorer
Flesch Reading Ease and Flesch-Kincaid Grade Level for any text.
SQL Formatter
Format a single-line SQL query into readable multi-line SQL.