Free Developer Tools - JSON, Base64, UUID, Regex

📝

JSON Formatter

Data Processing

Format, validate, and beautify JSON data with syntax highlighting. Perfect for debugging API responses and cleaning up messy JSON strings.

Real-time JSON validation
Syntax highlighting and indentation
Minify and prettify options
Error detection and highlighting
Copy formatted output

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🔒

Base64 Encoder/Decoder

Encoding

Encode and decode Base64 strings with support for text and file uploads. Essential for data transmission and storage scenarios.

Text and file encoding/decoding
Real-time conversion
Support for various character encodings
Download decoded files
URL-safe Base64 variant

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🆔

UUID Generator

Utilities

Generate universally unique identifiers (UUIDs) in various formats. Perfect for database keys, session IDs, and unique references.

UUID v1, v4, and v5 generation
Bulk generation (up to 1000 UUIDs)
Uppercase and lowercase formats
With or without hyphens
Copy individual or all UUIDs

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🔍

Regex Tester

Pattern Matching

Test and debug regular expressions with real-time matching and detailed explanations. Includes common regex patterns and flag support.

Real-time regex testing
Match highlighting and groups
Common regex library
Flag support (global, multiline, etc.)
Match count and details

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🔗

UTM Builder

Marketing Analytics

Build campaign tracking URLs for Google Analytics. Generate utm_source, utm_medium, utm_campaign and more. Preserve existing query parameters and copy in one click.

UTM parameter generator
URL validation and warnings
Preserve existing query params
Replace existing UTM tags
Copy full URL or query string

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🤖

robots.txt Generator

SEO

Generate a robots.txt file with common presets (allow all, disallow all, block /admin) and an optional Sitemap URL. Copy or download instantly — runs entirely in your browser.

Preset templates
Allow & Disallow rule editor
Optional Sitemap directive
Copy to clipboard
Download robots.txt

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🗺️

XML Sitemap Generator

SEO

Generate a valid sitemap.xml from a list of URLs (one per line). Add optional lastmod dates, set changefreq/priority defaults, and export in one click — runs entirely in your browser.

Optional global + per-URL lastmod
Changefreq & priority defaults
HTTPS normalization + trailing slash toggle
De-dupe & sort options
Copy or download sitemap.xml

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🌐

Hreflang Tag Generator

SEO

Generate hreflang <link rel="alternate"> tags for international SEO. Add language/region + URL rows, include x-default, validate formats, and export in one click.

Language/region + URL row editor
Optional x-default tag
ISO-format validation + auto casing
Trailing slash normalization
Copy or download tags

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🏷️

Meta Title & Description Preview

SEO

Preview how your title and description may appear in Google results. Includes character counts, pixel-width approximation, desktop/mobile toggle, and one-click copy for meta and OpenGraph tags.

Live SERP snippet preview
Character + pixel width checks
Desktop & mobile toggle
Copy meta title + description tags
Optional OpenGraph & Twitter tags

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📄

Schema Markup Generator (FAQ + HowTo)

SEO

Generate clean, copy-ready JSON-LD for FAQPage and HowTo schema. Add, remove, and reorder rows, validate required fields, and export in one click.

FAQ Q&A row editor (reorder + duplicate)
HowTo step builder
Validation + character guidance
Preview JSON output
Copy or download JSON-LD

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🤖 AI Developer Tools

AI Token Counter & Cost Calculator

NEW

Count tokens and estimate costs across GPT-4o, Claude, Gemini, Llama, and Mistral models. Includes batch cost projections.

8 major AI models supported
Real-time token counting
Input/output cost breakdown
Batch cost projections

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AI System Prompt Builder

NEW

Build structured system prompts with templates, variables, and best practices. 16 pre-built templates for common AI use cases.

Structured prompt builder with live preview
16 ready-to-use templates
Variable placeholders support
Prompt engineering tips

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Function Calling Schema Builder

NEW

Visual builder for AI function/tool schemas. Export for OpenAI, Anthropic, Gemini, and MCP with one click.

4 provider formats (OpenAI, Anthropic, Gemini, MCP)
Nested object & array support
Import existing schemas
Validation & syntax highlighting

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RAG Cost & Chunking Calculator

NEW

Estimate embedding, chunking, and vector DB costs for your RAG pipeline. Compare models and storage options.

6 embedding models with real pricing
6 vector databases compared
Chunking strategy calculator
Monthly cost projections

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Structured Output Schema Generator

NEW

Define your JSON structure visually, export as JSON Schema, Pydantic, Zod, or TypeScript. Import from JSON or generate from description.

4 output formats (JSON Schema, Pydantic, Zod, TS)
Nested objects & array support
Import JSON or generate from text
Sample JSON preview

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MCP Config Generator

NEW

Build Model Context Protocol server configs visually. Generate Python/TypeScript scaffolds and Claude Desktop configs.

Tools, Resources & Prompts builders
Python & TypeScript SDK scaffolds
Claude Desktop config export
Import existing MCP configs

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AGENTS.md / AI Config Generator

NEW

Generate AGENTS.md, .cursorrules, .clinerules, and system prompts via a guided wizard. 6 starter templates included.

5 output formats (AGENTS.md, Cursor, Cline, etc.)
4-step guided wizard
6 template starters
One-click copy & download

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AI API Response Converter

NEW

Convert API responses between OpenAI, Anthropic, and Gemini formats. Handles text, tool calls, streaming, and usage stats.

6 format auto-detection
Tool call conversion across providers
Field mapping annotations
8 pre-loaded examples

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AI Model Comparison Table

NEW

Compare 22+ AI models across pricing, context windows, and capabilities. Filter, sort, and compare side-by-side.

22 models, 8 providers
Sortable & filterable columns
Side-by-side comparison mode
Color-coded pricing

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AI API Key Validator

NEW

Test your API keys for OpenAI, Anthropic, Gemini, Mistral, Groq, and Together AI. Keys never leave your browser.

6 providers supported
Model list & rate limit info
100% browser-side (no server)
CORS detection with curl fallback

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UCP Readiness Checker

NEW

Validate a merchant’s Universal Commerce Protocol profile at /.well-known/ucp. Checks version, service bindings (REST/MCP/A2A), checkout capability, and generates a copyable readiness report.

Fetch + CORS detection with curl fallback
Paste JSON mode
Readiness score (0–100) + issues list
Links to UCP docs

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