Free Developer Tools
Free online developer utilities: format JSON, encode Base64, decode JWT, generate UUIDs, convert CSV and encode URLs. Runs locally in your browser.
120 tools in this collection — free, private and instant.
Data formats
JSON Formatter & Validator
Beautify, validate and prettify any JSON string.
JSON to CSV Converter
Convert JSON arrays to comma-separated values.
CSV to JSON Converter
Convert CSV data to JSON in one click.
JWT Decoder
Decode header and payload of any JSON Web Token.
Markdown to HTML Converter
Preview and convert Markdown to clean HTML.
FAQ Page Schema Markup Generator
Generate valid FAQPage JSON-LD structured data for rich results and AI search.
Article Schema Markup Generator
Generate valid Article JSON-LD structured data for rich results and AI search.
Blog Posting Schema Markup Generator
Generate valid BlogPosting JSON-LD structured data for rich results and AI search.
Product Schema Markup Generator
Generate valid Product JSON-LD structured data for rich results and AI search.
Local Business Schema Markup Generator
Generate valid LocalBusiness JSON-LD structured data for rich results and AI search.
Organization Schema Markup Generator
Generate valid Organization JSON-LD structured data for rich results and AI search.
Website Schema Markup Generator
Generate valid WebSite JSON-LD structured data for rich results and AI search.
Encoding
Base64 Encoder / Decoder
Encode and decode text to and from Base64.
URL Encoder / Decoder
Percent-encode and decode URLs and query strings.
HTML Encoder / Decoder
Escape HTML entities and reverse them.
HTML Encoder
Escape HTML special characters safely.
URL Encoder
Percent-encode text for safe use in URLs.
Base64 Encoder
Encode text to Base64 in your browser.
Base64 Decoder
Decode Base64 back to readable text.
Text to Hex
Convert text into hexadecimal bytes.
ROT13 Encoder / Decoder
Apply the classic ROT13 substitution cipher.
Identity & auth
Web & colour
Meta Tag Generator
Generate SEO title, description and OpenGraph meta tags.
URL Slug Generator
Turn any title into a clean SEO-friendly URL slug.
Meta Tag Generator
Build a complete <head> meta block from title, description and keywords.
Twitter Card Generator
Generate twitter: meta tags for large-image link previews.
Robots Meta Tag Generator
Build robots directives such as noindex, nofollow and max-snippet.
URL Slug Generator
Convert titles into clean, SEO-friendly URL slugs.
Hex to Text
Convert hex bytes back into text.
WordPress SEO Tools
Generate WordPress-ready SEO title, meta description and slug in one pass.
URL Shortener
Create clean, shareable slugs and a tidy canonical URL for any link.
RGB to HEX Converter
Convert 'r,g,b' values into a HEX colour code.
More free developer tools
Meta Title Length Checker
Check whether your title tag fits Google's pixel limit.
Meta Description Length Checker
Validate meta description length before you publish.
Open Graph Tag Generator
Create og: tags so links preview correctly on social platforms.
Canonical Tag Generator
Produce canonical link tags for one or many URLs.
Hreflang Tag Generator
Generate hreflang alternates for multilingual sites.
Robots.txt Generator
Create a robots.txt file with your disallow rules and sitemap.
XML Sitemap Generator
Turn a list of URLs into a valid XML sitemap.
Sitemap Index Generator
Combine multiple sitemaps into a sitemap index file.
Sitemap URL Extractor
Pull every <loc> URL out of a sitemap XML file.
Breadcrumb Schema Markup Generator
Generate valid BreadcrumbList JSON-LD structured data for rich results and AI search.
How-To Schema Markup Generator
Generate valid HowTo JSON-LD structured data for rich results and AI search.
Video Schema Markup Generator
Generate valid VideoObject JSON-LD structured data for rich results and AI search.
Event Schema Markup Generator
Generate valid Event JSON-LD structured data for rich results and AI search.
Recipe Schema Markup Generator
Generate valid Recipe JSON-LD structured data for rich results and AI search.
Review Schema Markup Generator
Generate valid Review JSON-LD structured data for rich results and AI search.
Person Schema Markup Generator
Generate valid Person JSON-LD structured data for rich results and AI search.
Job Posting Schema Markup Generator
Generate valid JobPosting JSON-LD structured data for rich results and AI search.
Software Application Schema Markup Generator
Generate valid SoftwareApplication JSON-LD structured data for rich results and AI search.
Course Schema Markup Generator
Generate valid Course JSON-LD structured data for rich results and AI search.
Q&A Page Schema Markup Generator
Generate valid QAPage JSON-LD structured data for rich results and AI search.
Keyword Density Checker
Find your top keywords and their density percentage.
Two-Word Phrase (Bigram) Extractor
Discover the most repeated two-word phrases in your copy.
Long-Tail Keyword Generator
Turn a seed keyword into ready-to-target long-tail variations.
Question Keyword Generator
Generate who/what/why/how question keywords from a topic.
About these tools
A pasteboard of the small utilities you reach for while debugging: pretty-printing a JSON payload, decoding a JWT to check its claims, converting CSV to JSON, or generating a UUID for a test fixture.
Because everything runs client side, you can safely paste tokens and API responses — no data is logged or sent to a backend.
Popular searches
Frequently asked questions
Is it safe to paste a production JWT here?
The decoder runs in your browser and never transmits the token, but treat any token you paste anywhere as worth rotating if it is highly sensitive.
Does the JSON formatter validate as well as format?
Yes. Invalid JSON reports the parse error and character position instead of silently failing.
Are the generated UUIDs version 4?
Yes, they use the browser's cryptographic random source.
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