24 free tools · No sign-up · Private

Tools for people who build with AI — and everyone else

Chat with Claude using your own key, engineer better prompts, configure Claude Code, and get everyday developer and writing jobs done. Everything runs locally in your browser.

AI Tools (MCP)

Free MCP Server

A free, stateless MCP server with tools AI is bad at doing in its head: exact math, unit & time-zone conversion, date math, cron, hashing, encoding, regex, JSON and Claude pricing. Connect it to Claude Code, Claude Desktop, claude.ai or the API.

MCP Tool Studio

Design a personal MCP server in the browser: knowledge-base lookups, templates, random pickers, multi-step pipelines and slash-command prompts. Your server is encoded in its URL — nothing is stored.

Connect your AI

AI Playground

Bring your own Anthropic API key and chat with any Claude model right in the browser — streaming, system prompts, effort control, token usage and cost per message.

Prompt Lab

Write a prompt template with {{variables}}, load rows from CSV, and run them in batch against one or two Claude models side by side. Export results to CSV.

Prompting

Prompt Builder

Build clear, structured prompts with role, context, task, constraints, examples and output format, then copy a ready-to-use prompt or API request.

Prompt Library

Browse dozens of high-quality prompts for coding, writing, analysis and business. Fill in the blanks, then copy, open in Claude, or run in the Playground.

Tool Definition Builder

Create tool definitions for Claude tool use (function calling) with a visual parameter editor. Exports API JSON, Python and TypeScript, and can infer a schema from sample JSON.

Claude Code

CLAUDE.md Generator

Generate a focused CLAUDE.md for your repository: stack, commands, conventions, architecture notes and guardrails Claude Code reads every session.

Settings & Permissions Builder

Point-and-click builder for Claude Code settings.json: allow/ask/deny permission rules, hooks, environment variables and model defaults.

MCP Config Builder

Configure stdio and HTTP MCP servers and get a ready .mcp.json, Claude Desktop config, and the matching `claude mcp add` commands.

Skill & Subagent Builder

Create Agent Skills, custom subagents and slash commands with valid frontmatter, a clear description that triggers reliably, and best-practice structure.

Cost & Context

Token & Cost Calculator

Paste text or enter token counts to estimate per-request and monthly cost across every current Claude model, with prompt caching and batch discounts.

Context Packer

Drop in files or paste snippets and pack them into a single XML-tagged context block with token estimates per document — ideal for long-context prompts.

Model Picker

A quick guided wizard that recommends a Claude model, effort level and features (caching, batch, thinking) for your use case — with a cost estimate and starter code.

Developer Utilities

JSON Toolkit

Pretty-print and validate JSON with precise error locations, convert between JSON, YAML and CSV, explore it as a tree, and generate TypeScript interfaces.

Text Diff

See exactly what changed between two versions of text, code or prompts — side-by-side or unified view, word-level highlights, and ignore-whitespace options.

Regex Tester

Write a regex, see matches highlighted live with capture groups, try replacements, and get a plain-English explanation. Includes a library of common patterns.

Encode, Decode & Hash

Encode and decode Base64, URL and HTML entities, inspect JWT tokens, and generate SHA-1/256/384/512 hashes — all locally in your browser.

Generators

Generate UUID v4/v7, strong passwords and passphrases with strength meter, lorem ipsum, and random sample data — cryptographically secure.

Cron Expression Helper

Paste a cron expression to get a plain-English explanation and the next run times, or build one visually from common schedules.

Timestamp Converter

Convert Unix timestamps (seconds or ms) to dates and back, view the time across multiple time zones, and compute date differences.

Color Tools

Convert between HEX, RGB, HSL and OKLCH, check WCAG contrast ratios, and generate tints, shades and harmonious palettes as CSS variables.

Text & Writing

Markdown Editor

A split-pane Markdown editor with live preview, formatting toolbar, table generator, and export to HTML or .md. Great for READMEs and AI outputs.

Text Toolkit

Count words, characters, sentences and reading time; convert case; remove duplicates; sort lines; and clean AI text (smart quotes, em dashes, markdown, invisible characters).