JWT Decoder
Decode and validate JWT tokens in seconds with full security right in your browser.
jwttokendecodersecurityauth
rundev
A collection of fast and private developer tools focused on productivity, diagnostics, and technical SEO. Everything runs directly in your browser, following best practices for useful and accessible content.
JSON Formatter
Format, validate, and organize JSON for readability with instant error highlighting.
jsonformatvalidatorapidata
Word Count
Count words, sentences, and estimate reading time to optimize content and SEO.
wordstextseoreadingcopy
PDF & Markdown Converter
Convert PDF to Markdown and Markdown to PDF in your browser, keeping headings, lists, and tables.
pdfmarkdownmdconvertdocs
Morse Code Translator
Translate text to Morse code and back, and hear it played at real transmission speed.
morsecodetranslatordecoderaudio
Random generators
Pick a random word, number, colour, animal or date — or split a list of names into teams. Every one runs in your browser.
Text style generators
Bold, cursive, gothic, tiny, upside down and more — Unicode styles that survive a paste into a bio, a username or a chat.
Developer tools that run in your browser, not on our servers
Most free online tools work the same way: you paste your data into a form, it travels to a server you know nothing about, and it comes back processed. That is fine for a throwaway string and a real problem for a production JWT, a client contract, or an API response with customer records in it. RunDev takes the opposite approach. Every tool here runs entirely inside your browser using standard web APIs, so your data never leaves your machine — there is no upload, no queue, and no copy of your input sitting in someone else’s database.
That design has a practical side effect: the tools keep working after the page has loaded, even offline. It also means we cannot see what you paste, which is the point.
What you will find here
- Decoders and inspectors for the formats that show up in day-to-day backend work — JWT payloads, JSON responses, and their structure.
- Converters that move content between formats without losing its structure, like turning a PDF into editable Markdown or a Markdown document into a printable PDF.
- Text analysis for writing and SEO work: word counts, character counts, and reading time estimates.
No sign-up, no limits, no watermarks
There is no account to create and no daily quota. The tools are free because they cost us almost nothing to run — the work happens on your computer, not ours. Nothing is watermarked, nothing is truncated after the third use, and no result is held behind an upgrade prompt.
Built for speed
Every tool is a single page that loads once and responds instantly, with no round trip between typing and seeing the result. Heavier features load their code only when you actually use them, so opening a tool stays fast even when the work behind it is not.