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JustDevTools
  • JSON formatter and validator
    Format, minify and validate JSON, with the exact line and column of any syntax error.
  • JWT decoder
    Read a JWT's header and payload, with issued-at and expiry times shown as real dates.
  • Base64 encoder and decoder
    Encode and decode Base64 and Base64URL, with full Unicode support.
  • JSON to TypeScript, Zod and Java
    Paste a JSON response and get TypeScript interfaces, a Zod schema or Java classes with Jackson annotations.
  • YAML to JSON converter
    Convert YAML to JSON and JSON to YAML, with the exact line of any syntax error. Handles multi-document files.
  • Regex tester
    Test JavaScript regular expressions with live match highlighting, capture groups and replace preview.
  • URL encoder and decoder
    Percent-encode and decode URLs and query values, and break a URL into its parts and parameters.
  • Unix timestamp converter
    Convert Unix timestamps in seconds or milliseconds to dates, and dates back to timestamps.
  • Cron expression explainer
    See what a cron expression means in plain English, what each field does and the next times it will run.
  • JSON to CSV converter
    Turn a JSON array into CSV for Excel or Google Sheets, or a CSV file into JSON. Nested objects become columns.
  • UUID generator and inspector
    Generate UUID v4 and time-ordered v7 in bulk, or paste a UUID to see its version and timestamp.
  • Text diff checker
    Compare two texts line by line and see exactly what was added, removed or changed.
  • Hash and HMAC generator
    SHA-256, SHA-1, SHA-384 and SHA-512 hashes and HMAC signatures of text, in hex or Base64.
  • Markdown previewer
    Write Markdown on the left and see it rendered live on the right, with GitHub-style tables and task lists.

Privacy policy

Last updated 9 November 2026

The short version

JustDevTools does not collect, store or share what you type or paste into its tools. Every tool runs entirely in your browser. There are no accounts, no cookies, no analytics, no tracking and no ads.

What you paste into the tools

JSON, tokens, text, YAML, CSV, regular expressions and anything else you enter is processed by JavaScript in your own browser tab. It is never sent to our server or anyone else's, never logged and never saved. When you close or reload the tab, it is gone.

You can check this yourself: open your browser's developer tools, go to the Network tab and use any tool. No request carries your input.

What is stored on your device

One setting: if you switch between light and dark mode, your choice is saved in your browser's local storage under the name theme, so the site remembers it next time. It never leaves your device. You can remove it by clearing this site's data in your browser settings.

The site sets no cookies.

Server logs

Like any website, the pages are delivered by a hosting provider. When your browser requests a page, the provider's servers may record standard technical information such as your IP address, the page requested, the time and your browser type, to deliver the site and protect it from abuse. These logs never include what you type into the tools, because that never reaches the server. We do not use these logs to identify or profile you.

Content from other websites

The site loads nothing from other websites: its fonts, scripts and styles are all served from this domain. There are two cases where your browser may contact another website, and both are your choice:

  • Images in the Markdown previewer. Images are not loaded by default. If you turn on “Load images”, your browser downloads each image from the address in your Markdown, and that website can see your IP address, like any image on the web.
  • Links. Links to other websites, including links in your own Markdown, take you to that website, which has its own privacy policy.

Children

The site is a set of developer tools. It is not aimed at children and collects no information from anyone.

Changes to this policy

If the site ever starts collecting any data, for example through analytics or advertising, this page will be updated before that happens, and the date at the top will change.

Contact

Questions about privacy? Get in touch.