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filemarkr

60+ free developer tools that run entirely in your browser — JSON formatter, JWT decoder, Base64, diff checker, regex tester, hash generator and more. No upload, no sign-up, completely private.

JSON & Data

  • JSON Formatter
  • JSON Minifier
  • JSON Validator
  • JSON to CSV
  • CSV to JSON
  • JSON to YAML

Encode & Decode

  • Base64 Encode / Decode
  • Base64 to Image
  • Image to Base64
  • URL Encode / Decode
  • HTML Entity Encoder
  • JWT Decoder

Text Tools

  • Text Diff Checker
  • Case Converter
  • Word & Character Counter
  • Slug Generator
  • Remove Duplicate Lines
  • Sort Text Lines

Generators

  • UUID Generator
  • Password Generator
  • Lorem Ipsum Generator
  • QR Code Generator
  • Random Number Generator
  • NanoID Generator

Popular Guides

  • How to Format and Pretty-Print JSON (Without Breaking It)
  • How to Minify JSON and Shrink Your API Payloads
  • How to Validate JSON and Pinpoint the Exact Syntax Error
  • How to Convert JSON to CSV for Excel and Google Sheets
  • How to Convert CSV to JSON (With Proper Header Detection)
  • All guides →

Explore

  • All Tools
  • JSON Formatter
  • JWT Decoder
  • Diff Checker
  • UUID Generator

Company

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Our Promise

  • 100% in your browser
  • Zero uploads
  • No sign-up, always free

© 2026 filemarkr. Designed & developed by Naved Naik.  All processing happens locally in your browser.

Terms of Use

Last updated: July 2026

Acceptance

By using filemarkr, you agree to these terms. If you do not agree, please do not use the site.

The service

filemarkr provides free, browser-based developer tools "as is." We work hard to keep them accurate and reliable, but we make no warranties about correctness, availability, or fitness for a particular purpose.

Your responsibility

You are responsible for the data you process and for verifying results before relying on them in production. Do not use the tools for any unlawful purpose.

Limitation of liability

To the maximum extent permitted by law, filemarkr and its author are not liable for any damages arising from the use of, or inability to use, the tools.

Changes

We may update these terms from time to time. Continued use of the site after changes constitutes acceptance of the revised terms.