Developer Tools
JSON, HTML, CSS, and code utilities
Our developer tools cover the essentials of daily coding work — JSON formatting and validation, JWT decoding, UUID generation, Base64 encoding, cryptographic hashing, regex testing, and URL analysis. They're built for the moments you need a quick, trustworthy utility mid-task: debugging an API response, decoding a token a teammate sent you, or checking a regex before it ships. Nothing you paste is sent anywhere — nearly every tool here runs the parsing and encoding logic directly in your browser tab, so you can use them on internal or sensitive data without a second thought. No sign-up, no uploads, no limits.
All Developer Tools
17 tools ready to use.
JWT Decoder
Decode and inspect JSON Web Tokens securely in your browser. View headers, payloads, claims, and expiration status.
Hash Generator
Generate secure hashes instantly using MD5, SHA-1, SHA-256 and SHA-512. Hash text and files locally with zero uploads.
Base64 Encoder & Decoder
Encode and decode Base64 instantly with Unicode, file, and live mode support.
UUID Generator
Generate UUID v1, v4, and v7 instantly with validation, formatting, and bulk export.
Password Generator
Generate strong, secure passwords with customizable rules.
JSON Formatter & Validator
Format, validate, and beautify JSON data instantly.
JSON Validator
Validate JSON with human-friendly error messages and instant feedback.
JSON Diff
Compare JSON files visually. Highlight additions, removals and modifications with side-by-side and inline comparison.
Regex Tester & Builder
Test, debug, explain and build regular expressions visually with live highlighting, token explanations, and a built-in debugger.
URL Toolkit
Analyze, encode, decode, validate and inspect URLs with ForgePlug's advanced URL Toolkit. Includes query parameter editor, URL builder, UTM builder, security analyzer, QR code generation and browser-only processing.
Mock API Studio
Create, test and consume realistic fake REST APIs instantly — prebuilt datasets, full CRUD, filtering, sorting, pagination, mock auth, error & latency simulation, GraphQL, OpenAPI and 15-language code generation. Free, private, browser-first.
Site Health Check
Check a domain's SSL certificate, DNS records, HTTP security headers, and robots.txt/sitemap in one report with a plain-English pass/warn/fail badge.
SSL Checker
Check any domain's SSL/TLS certificate — expiry date, issuer, chain completeness, protocol version, and cipher suite — with plain-English warnings.
DNS Propagation Checker
Check A, AAAA, MX, TXT, and NS records across Cloudflare, Google, and Quad9 to see if your DNS changes have finished propagating.
Security Headers Checker
Check whether a site sends Strict-Transport-Security, CSP, X-Frame-Options, and the other HTTP headers browsers use to defend against common attacks.
Robots.txt Tester
Validate robots.txt rules and check that every declared sitemap actually loads — flags an accidental Disallow: / and broken sitemap URLs.
Bulk URL Checker
A free bulk URL checker and redirect checker: check up to 100 URLs at once for status codes, redirect chains, and common issues. Paste URLs, upload a CSV, or enter a sitemap — free, no signup.
Recently Added
The newest tools in this category.
Bulk URL Checker
A free bulk URL checker and redirect checker: check up to 100 URLs at once for status codes, redirect chains, and common issues. Paste URLs, upload a CSV, or enter a sitemap — free, no signup.
Site Health Check
Check a domain's SSL certificate, DNS records, HTTP security headers, and robots.txt/sitemap in one report with a plain-English pass/warn/fail badge.
SSL Checker
Check any domain's SSL/TLS certificate — expiry date, issuer, chain completeness, protocol version, and cipher suite — with plain-English warnings.
DNS Propagation Checker
Check A, AAAA, MX, TXT, and NS records across Cloudflare, Google, and Quad9 to see if your DNS changes have finished propagating.
Guides for Developer Tools
Learn the formulas, assumptions, and best practices behind developer tools in our Developer Guides.
How to Test a REST API Without Building a Backend
You don't need a server to design, test, and document an API. Here's how mock APIs work and how to prototype requests, errors, and auth.
What Is JSON Schema and When Should Developers Use It?
JSON Schema describes the shape of JSON data — required fields, types, ranges — in a machine-checkable form. Here's when it's worth using.
How to Format JSON When Debugging API Responses
Raw API responses arrive as one long unreadable line. Here's how to format them, what the common errors mean, and when formatting alone won't save you.
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Developer Tools — Frequently Asked Questions
Common questions about using developer tools on ForgePlug.