filemarkr
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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
  • Privacy
  • Terms
  • Sitemap

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.

About filemarkr

filemarkr is a free collection of 65+ developer tools that run entirely in your web browser. There are no accounts, no uploads, and no limits — just fast, focused utilities for the work developers do every day.

Why we built it

Most online dev tools bury a simple task under ads, pop-ups, and upload prompts that quietly send your data to a server. We wanted the opposite: a calm, fast, private toolbox where a JSON payload, a JWT, or a config file never leaves your device.

How it works

Every tool is implemented in JavaScript that runs on your machine. When you format JSON, decode a token, or generate a hash, the computation happens in your browser tab. Nothing is transmitted, logged, or stored. Close the tab and your data is gone.

Our principles

  • Private by design — local-first processing, zero uploads.
  • Fast — no round-trips, no waiting rooms, instant results.
  • Free — no paywalls, no watermarks, no sign-up.
  • Focused — one clear job per tool, done well.

Private

Instant

Free forever

Built by Naved Naik. Explore all 65 tools or read the guides.