Developer01
Number Base Converter
Convert integers exactly between bases 2–36, even beyond the safe integer range.
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Free tools for everyday digital work
32 free tools for developer data, text, images, XML, schedules, Markdown, dates, URLs, CSV, HTML, and CSS. Tools process input in this browser and do not upload it to a 77 Toolkit server.
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Developer
Fix broken JSON
Repair copied API data, format it, and review the result.
Open tool ImageMake an image smaller
Adjust JPEG or WebP quality and compare the file size locally.
Open tool TextClean copied AI text
Remove Markdown-style formatting and keep readable paragraphs.
Open tool ImageRemove image metadata
Re-encode an image before sharing it. Review the privacy limitations.
Open tool WebConvert CSV to JSON
Move quoted tabular data between CSV and JSON object arrays.
Open tool DeveloperRead a Unix timestamp
Translate seconds or milliseconds into UTC and local time.
Open tool32 tools · 4 categories
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Developer
14 toolsDeveloper02
JSON String Escaper
Escape plain text as a JSON string or restore a quoted JSON string to readable text.
Developer04
JSON Fix
Repair malformed JSON and turn it into clean, readable data.
Developer05
JSON Diff
Compare two JSON documents and inspect added, removed, and changed values.
Developer06
Timestamp Converter
Convert Unix timestamps and local dates while keeping an eye on the current time.
Developer07
JWT Decoder
Decode JWT headers and payloads locally without sending tokens to a server.
Developer08
Base64 Encoder
Encode or decode UTF-8 text with standard and URL-safe Base64.
Developer09
Regex Tester
Test regular expressions, inspect capture groups, and highlight every match.
Developer10
UUID Generator
Generate secure UUID v4 values in batches and validate existing UUIDs.
Developer11
Hash Generator
Calculate SHA-256, SHA-384, or SHA-512 hashes for text and local files.
Developer12
XML Formatter
Validate, format, or minify XML while keeping the document in your browser.
Developer13
Cron Expression Inspector
Validate five-field cron expressions and preview upcoming local run times.
Developer14
Password Generator
Generate configurable passwords with cryptographically secure browser randomness.
Developer15
Date Calculator
Measure calendar spans and add or subtract days, weeks, months, or years.
Text
6 toolsText16
Text Clean
Remove copied rich-text and AI formatting while preserving readable structure.
Text17
Text Diff
Compare text line by line with a clear view of additions and removals.
Text18
Case Converter
Switch text between common writing and programming case styles.
Text19
Line Processor
Clean, sort, reverse, number, prefix, or deduplicate lists of lines.
Text20
Word Counter
Measure words, characters, sentences, lines, reading time, and common terms.
Text21
Markdown Preview
Preview a practical Markdown subset without executing pasted HTML or scripts.
Image
6 toolsImage22
Color Spectrum
Extract dominant colors, inspect pixels, and export palettes from an image.
Image23
Image Compressor
Reduce image file size locally with an adjustable quality setting.
Image24
Image Resizer
Resize images to exact dimensions while optionally preserving aspect ratio.
Image25
Image Format Converter
Convert images between PNG, JPEG, and WebP entirely in the browser.
Image26
Color Contrast Checker
Check foreground and background colors against WCAG contrast targets.
Image27
Image Metadata Remover
Strip EXIF and other metadata by safely re-encoding an image locally.
Web
6 toolsWeb03
UTM Link Builder
Build campaign URLs with encoded UTM parameters while preserving existing query values.
Web28
URL Parser
Break an absolute URL into its origin, path, query parameters, and fragment.
Web29
URL Encoder
Encode or decode URL components without sending addresses to a remote service.
Web30
CSV ↔ JSON Converter
Convert quoted CSV records and JSON object arrays in either direction locally.
Web31
HTML Entity Encoder
Encode HTML-sensitive characters or decode named and numeric character references.
Web32
CSS Unit Converter
Compare px, rem, em, vw, and vh values using explicit layout assumptions.
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Practical guides
Get the result right
Practical explanations, review steps, and limitations for developer, web, text, and image workflows.
Developer data
7 min read · Read guide →How to repair invalid JSON without changing its meaning
A careful workflow for fixing JSON syntax, reviewing inferred changes, and validating the result before it returns to an application.
Image workflow
8 min read · Read guide →PNG, JPEG, and WebP: choose by image content
A practical comparison of common browser image formats, compression artifacts, transparency, resizing, and repeat export quality.
Web addresses
8 min read · Read guide →URL encoding without broken query parameters
Understand URL structure, component encoding, repeated query keys, plus signs, Unicode hosts, and the difference between parsing an address and trusting it.
How the collection is maintained
Useful output needs a reviewable method
Every published tool combines working browser functionality with task-specific guidance and explicit limitations.
Local by design
Text and selected files are processed with browser APIs. Tools do not fetch pasted URLs or send input to a 77 Toolkit backend.
Specific, not generic
Each page explains its own workflow, assumptions, failure cases, and better alternatives instead of repeating one template description.
Built for verification
Input stays visible, results can be reviewed before copying, and the production build checks metadata, links, page depth, and crawlability.
Read the editorial and testing policyRead the accessibility statement
About 77 Toolkit
77 Toolkit collects small, useful browser tools in one place. Text, tokens, images, URLs, and tabular data are processed locally whenever the browser provides the required capability. Learn how the site is built and maintained.