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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

  • About
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  • Terms
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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.

Privacy Policy

Last updated: July 2026

The short version

filemarkr processes your data entirely inside your browser. We do not upload, collect, store, or sell the content you paste into any tool.

Data you enter into tools

Text, files, tokens, and other input you provide to a tool are processed locally on your device using JavaScript. This data is never transmitted to our servers because there is no server-side processing for the tools.

Local storage

We store a single preference in your browser's local storage: your chosen light or dark theme. This never leaves your device and contains no personal information.

Analytics

We may use privacy-respecting, aggregate analytics to understand which tools are popular. Any such analytics do not capture the content you enter into tools.

Cookies

filemarkr does not use tracking or advertising cookies.

Third-party links

Guides and pages may link to third-party sites. We are not responsible for the privacy practices of those sites.

Contact

Questions about this policy? Reach out via the author's site linked in the footer.