FREE DEVELOPER TOOLS

AI API Cost Calculator

Estimate cost per request, day, and month across Claude, GPT-5, and Gemini. Compare two models with prompt-caching and batch-mode discounts.

Token Estimator

Live token counts for Claude, GPT, and Llama with a context-window gauge. See approximate costs.

Prompt Tester

Analyze AI prompts for structure, cost, readability, and best practices. Improve before you ship.

AI Coding Tool Matrix

Compare 8 AI coding agents side by side - features, pricing, context windows, and recommendations.

JSON Formatter

Format, minify, and validate JSON. Paste messy data, get clean output.

JSON to TypeScript

Paste JSON, get TypeScript interfaces, Zod schemas, and Python dataclasses.

Regex Tester

Test regular expressions in real time. See matches highlighted as you type.

Diff Viewer

Compare two blocks of text side by side. See additions, removals, and changes.

cURL to Code

Convert cURL commands to JavaScript, Python, Go, and more. Paste and go.

JWT Decoder

Decode JSON Web Tokens. Inspect header, payload, and signature.

Cron Builder

Build cron expressions visually. See next run times in plain English.

API Tester

Test any API endpoint. Send requests, see response headers, body, timing, and status codes.

Estimate cost per request, day, and month across Claude, GPT-5, and Gemini. Compare two models with prompt-caching and batch-mode discounts.

Live token counts for Claude, GPT, and Llama with a context-window gauge. See approximate costs.

Analyze AI prompts for structure, cost, readability, and best practices. Improve before you ship.

Compare two AI prompts side by side with line-level diffs. Spot changes between prompt versions.

Compare 8 AI coding agents side by side - features, pricing, context windows, and recommendations.

Generate a CLAUDE.md config for Claude Code. Pick your stack, get a ready-to-use project file.

Generate MCP server configs for Claude Code and Cursor. Pick servers, add keys, download.

Generate .env files with preset templates for Next.js, Vercel AI SDK, Clerk, Supabase, Stripe, and more.

Format, minify, and validate JSON. Paste messy data, get clean output.

Paste JSON, get TypeScript interfaces, Zod schemas, and Python dataclasses.

Encode and decode Base64 strings instantly.

Encode and decode URL components. Handle special characters safely.

Encode and decode HTML entities. Keep special characters safe.

Convert between Unix timestamps and human-readable dates.

Convert between hex, RGB, and HSL color formats. Live preview swatch.

Convert between px, rem, em, and viewport units.

Test regular expressions in real time. See matches highlighted as you type.

Compare two blocks of text side by side. See additions, removals, and changes.

Format, beautify, and minify SQL queries. Uppercase keywords, indent subqueries.

Convert cURL commands to JavaScript, Python, Go, and more. Paste and go.

Write markdown on the left, see rendered HTML on the right. Live preview.

Convert between camelCase, snake_case, kebab-case, and more.

Count words, characters, sentences, and more. Analyze any text.

Generate placeholder text. Paragraphs, sentences, or words.

Beautiful code snippets with syntax highlighting. Pick a theme and language.

Create markdown tables visually with an interactive editor. Add rows, columns, and copy the result.

Generate Tailwind CSS class strings with live preview. Presets for cards, buttons, badges, and more.

Decode JSON Web Tokens. Inspect header, payload, and signature.

Generate cryptographic hashes. SHA-256, SHA-384, SHA-512, and SHA-1.

Generate unique identifiers. Click to create, click to copy.

Calculate Unix file permissions. Convert between numeric and symbolic notation.

Build cron expressions visually. See next run times in plain English.

Test any API endpoint. Send requests, see response headers, body, timing, and status codes.

Generate .gitignore files from preset templates. Combine, customize, and download.

Generate meta tags and OG tags with live Google, Twitter, and Facebook previews.

Validate YAML syntax, convert between YAML and JSON, pretty-print or minify.

Generate production-ready Dockerfiles with multi-stage builds and best practices.

Define endpoints and generate a complete Express.js mock server. Copy or download.

Edit TOML with syntax highlighting. Validate and convert between TOML, JSON, and YAML.

Build git commands visually. Select operations, configure flags, and get plain-English explanations.

Generate conventional commit messages with type, scope, and body. Clean, consistent git history.

Build professional README.md files interactively. Toggle sections, reorder, and preview live.

Paste your package.json and get instant analysis. Dependencies, stack detection, and health indicators.

Test robots.txt rules against URLs to verify allowed and disallowed paths for crawlers.

View and create tweets with live preview, code snippets, and image export.

The complete visual language - colors, typography, buttons, cards, and tokens.

74 free SVG logos for AI tools, languages, and infrastructure. Search, preview, copy.

Browse all pages on Developers Digest - blog posts, guides, tools, and more.