65 fast, private tools to format, convert, encode, and generate — right in your browser. No uploads. No sign-up.
JSON Formatter
Beautify and pretty-print JSON with a live tree view and error detection.
JSON Minifier
Compress JSON into a single line and see exactly how many bytes you saved.
JSON Validator
Validate JSON syntax and jump straight to the line and column of any error.
JSON to CSV
Convert a JSON array of objects into clean CSV, ready for Excel or Sheets.
CSV to JSON
Turn CSV rows into a JSON array of objects with header detection.
JSON to YAML
Convert JSON to readable YAML for configs, CI files and manifests.
YAML to JSON
Parse YAML into JSON and validate your config in one step.
JSON to XML
Convert JSON objects into well-formed, indented XML.
XML to JSON
Parse XML into a clean JSON structure you can work with.
JSON to TypeScript
Generate TypeScript interfaces from any JSON payload instantly.
JSON Diff
Compare two JSON documents and highlight every added, removed or changed value.
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal.
Color Converter
Convert colors between HEX, RGB, HSL and HSV with a live preview.
CSV to Markdown Table
Paste CSV and get a GitHub-flavored Markdown table you can drop into any README.
Markdown to HTML
Render Markdown to clean, sanitized HTML with a live preview.
HTML to Markdown
Convert HTML into tidy Markdown for docs, notes and issues.
Roman Numeral Converter
Convert numbers to Roman numerals and back, up to 3,999,999.
Text to Binary
Convert text to binary, hex, octal or decimal — and decode it back.
Base64 Encode / Decode
Encode text to Base64 and decode it back, with full Unicode support.
Base64 to Image
Preview and download an image from a Base64 or data-URI string.
Image to Base64
Turn any image into a Base64 data URI for CSS, HTML or JSON.
URL Encode / Decode
Percent-encode and decode URLs and query-string components safely.
HTML Entity Encoder
Encode and decode HTML entities to escape or unescape markup.
JWT Decoder
Decode a JSON Web Token to inspect its header, payload and expiry.
URL Parser
Break a URL into protocol, host, path, query params and hash.
Backslash Escape / Unescape
Escape and unescape strings for JSON, JavaScript and other languages.
SQL Formatter
Format and beautify SQL queries across MySQL, Postgres and more dialects.
XML Formatter
Pretty-print and indent XML, or collapse it back into one line.
HTML Beautifier
Format and indent messy HTML into clean, readable markup.
CSS Beautifier
Beautify and indent CSS with consistent spacing and formatting.
JavaScript Formatter
Format and beautify JavaScript with proper indentation and spacing.
CSS Minifier
Minify CSS by stripping comments and whitespace to shrink your stylesheet.
JavaScript Minifier
Minify JavaScript with a real Terser engine to reduce bundle size.
HTML Minifier
Compress HTML by removing comments and collapsing whitespace.
Text Diff Checker
Compare two blocks of text and highlight every difference line by line.
Case Converter
Convert text between camelCase, snake_case, kebab-case, Title Case and more.
Word & Character Counter
Count words, characters, sentences, lines and reading time as you type.
Slug Generator
Turn any title into a clean, URL-safe slug for pages and posts.
Remove Duplicate Lines
Strip duplicate lines from a list, with optional sorting and trimming.
Sort Text Lines
Sort lines alphabetically, numerically or reverse — case-sensitive or not.
Find and Replace
Find and replace text with plain-text or full regular-expression support.
Reverse Text
Reverse a string by characters, words or whole lines.
Markdown Viewer
Open and view any .md file as a clean, rendered document — drag, drop, read.
Markdown Editor & Preview
Write Markdown with a live, side-by-side rendered preview.
Remove Line Breaks
Remove or collapse line breaks and extra whitespace from text.
UUID Generator
Generate v4 and v1 UUIDs in bulk, ready to copy or download.
Password Generator
Create strong, random passwords with full control and a strength meter.
Lorem Ipsum Generator
Generate placeholder paragraphs, sentences or words for mockups.
QR Code Generator
Create a downloadable QR code from any link or text, right in the browser.
Random Number Generator
Generate random numbers in any range, with unique and sorted options.
NanoID Generator
Generate compact, URL-friendly NanoIDs with a custom size and alphabet.
Gitignore Generator
Build a .gitignore from templates for Node, Python, macOS and more.
Box Shadow Generator
Design CSS box-shadows visually and copy the exact code.
CSS Gradient Generator
Build linear and radial CSS gradients with a live preview.
Color Picker & Palette
Pick a color, get every format, and generate tints, shades and palettes.
Color Contrast Checker
Check text/background contrast against WCAG AA and AAA standards.
Meta Tag Generator
Generate SEO, Open Graph and Twitter meta tags from a simple form.
Regex Tester
Test regular expressions against text with live match highlighting.
Hash Generator
Generate MD5, SHA-1, SHA-256 and SHA-512 hashes from any text.
Bcrypt Generator
Hash a password with bcrypt and verify a value against a hash.
HTTP Status Codes
A searchable reference of every HTTP status code and what it means.
JSON Path Finder
Explore a JSON tree and copy the exact path to any value.
Everything runs on your device. Nothing is uploaded — ever.
No server round-trips, no waiting rooms. Results appear as you type.
No account, no paywall, no limits, no watermarks.
No. Every tool on filemarkr runs entirely inside your browser using JavaScript. Your data is processed in your device's memory and never leaves your tab, which makes it safe for confidential code, tokens, and documents.
filemarkr is a free collection of 65+ online developer tools that run entirely in your web browser. Nothing is uploaded, so you can format JSON, decode JWTs, encode Base64, compare text, test regex, and generate hashes without sending anything to the cloud.
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