ZKTOOL / LOCAL-FIRST TOOLS

Runs locally

Leave the complexity to the tools.

A quiet, local-first toolkit for formatting, debugging, converting, and testing.

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Explore by workflowStart with a focused set of tools

Formatting & Data Encoding & Characters Text Processing

43 tools available No account required All tools

All tools

43 tools available

Formatting & Data

07

JSON Formatter & Validator Validate, format, minify, escape, and inspect JSON with syntax highlighting, tree view, precise errors, and statistics. JSON JSON Format Converter Convert JSON to YAML, TypeScript interfaces, Go structs, or CSV. Convert SQL Formatter Format or minify SQL for common dialects and choose a keyword case style. SQL YAML Converter & Validator Convert YAML and JSON in both directions with live syntax validation and line/column errors. YAML cURL Command Parser Parse cURL commands into structured requests and generate fetch and Python requests code. HTTP Docker Run to Compose Parse a docker run command and generate modern Docker Compose YAML for common runtime options. Docker JSON Diff Compare two JSON structures by path and list added, removed, modified, and type-changed values. Diff

Encoding & Characters

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URL Encoder & Query Parser Encode and decode URLs, inspect query parameters, and convert between query strings and objects. URL Base64 Converter Encode and decode UTF-8 Base64, Hex, and Unicode escapes with byte statistics. Encoding Unicode Character Inspector Inspect code points and encodings character by character, including zero-width and invisible characters. Unicode HTML Entity Encoder & Decoder Encode special characters as named, decimal, or hexadecimal HTML entities and decode them again. HTML Chinese RMB Uppercase Converter Convert numeric RMB amounts to formal Chinese uppercase notation and convert them back to numbers. Currency Number Base Converter Convert binary, octal, decimal, hexadecimal, and custom bases from 2 to 36 with BigInt precision. Radix

Text Processing

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Regular Expression Tester Test JavaScript regular expressions with live highlights, capture groups, flags, and replacement previews. Regex Text Diff Compare two texts line by line and highlight additions, removals, and unchanged lines. Diff Text Case & Line Tools Convert camelCase, snake_case, and other naming styles, or deduplicate, sort, and clean lines. Text Markdown Preview & Publisher Render Markdown live, apply publishing themes, customize colors, and copy styled rich text or HTML. Markdown

Time & Scheduling

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Timestamp Converter Convert Unix timestamps and dates with automatic seconds/milliseconds detection, batch conversion, multiple formats, and time-zone comparison. Time Cron Expression Parser Parse five-field Cron expressions, explain each field, and preview the next ten run times. Cron Time Zone Meeting Planner Compare local times and working hours across cities to find practical international meeting times. Time zones Date Difference Calculator Calculate calendar days, business days, and calendar-unit differences, or add and subtract dates. Dates

Generators & Credentials

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Random ID Generator Generate UUID v4 values, passwords, tokens, numeric codes, and custom random strings in batches. Random Hash Calculator Calculate MD5, SHA-1, SHA-256, and SHA-512 hashes for text or files locally in your browser. Hash JWT Decoder & Verifier Decode JWT headers and payloads, inspect expiration, and verify HS, RS, and ES signatures locally. Token QR Code Generator Generate QR codes for links, text, and sharing in a separate service. External service Key Pair Generator Generate RSA, ECDSA, and Ed25519 key pairs locally and export PEM or JWK. Keys AES Encrypt & Decrypt Encrypt and decrypt text with AES-256-GCM and PBKDF2 password derivation entirely in your browser. Encryption X.509 Certificate Decoder Decode PEM certificates and inspect validity, SANs, public keys, fingerprints, and certificate chains. Certificates

Charts & Images

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Mermaid Diagram Editor Edit and render Mermaid flowcharts, sequence diagrams, and more with templates, pan and zoom, share links, and PNG/SVG export. Diagrams Color Converter & Contrast Checker Convert HEX, RGB, and HSL colors, generate shades, and check WCAG foreground/background contrast. Color Image Compressor & Converter Compress and convert images to WebP, JPEG, or PNG locally with adjustable quality and size. Images SVG Optimizer & Preview Optimize SVG markup locally, preview the result, and generate encoded or Base64 data URIs. SVG CSS Length Unit Explorer Compare px, rem, vw, and other CSS length units with adjustable visual examples. CSS HTML Drag and Drop Playground Test native HTML drag and drop, list sorting, file drops, and live event logs. DnD

Devices & Mobile

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QR Code Scanner Scan QR codes with a camera or image file entirely in your browser. Scanner EXIF Viewer & Remover Inspect photo metadata such as capture time, device, exposure, and GPS, then export a clean copy. EXIF Device Information Inspect screen size, DPR, viewport, safe areas, browser capabilities, and network state. Device Touch Event Tester Visualize multiple touch points, movement trails, pressure, dimensions, and pointer-event logs. Touch Sensor Viewer Visualize gyroscope, accelerometer, and compass readings on supported mobile devices. Sensors

Quick Reference

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Emoji Library Browse and search Emoji by category, keep favorites and recents, switch skin tones, and copy with one click. Unicode HTTP Status & MIME Reference Search common HTTP status codes and MIME types, then click any entry to copy it. Reference chmod Permission Calculator Convert Linux file permissions between checkboxes, octal values, symbolic notation, and chmod commands. Linux CIDR Subnet Calculator Calculate IPv4 networks, broadcasts, masks, host ranges, membership, and subnet splits. Networking