Audio & Video
Extract audio, transcode short files, and remux compatible media locally.
- Media Converter
KitLumi · Free browser-based utilities
Free online developer tools for everyday technical work
Format code, convert files, and work with images, PDFs, text, and network data. No account or installation required.
74published tools
73locally processed tools
Fast access
Most used tools
Twelve popular entry points cover structured data, encoding, text, identifiers, images, and PDFs.
Live
JSON Formatter
Format, validate, sort, and minify JSON with exact error locations.
LiveJSON Diff
Compare parsed JSON values and list structural changes by path.
LiveBase64
Convert text or files to and from Base64.
LiveURL Encoder
Encode or decode URL components and inspect query parameters.
LiveHash Generator
Calculate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 together.
LiveRegex Tester
Test regular expressions with matches and capture groups.
LiveTimestamp Converter
Convert Unix timestamps and human-readable dates.
LiveUUID Generator
Generate one or many standards-based UUIDs.
LivePassword Generator
Create strong passwords with clear entropy controls.
LiveImage Compressor
Reduce image size while controlling output quality.
LiveImage Converter
Convert PNG, JPEG, WebP, and supported AVIF images locally.
LivePDF Merge
Combine PDF files and arrange pages before export.
Start from the job
Browse by task
Use familiar actions when you know the job but not the exact tool name.
Format & Validate
Clean structured data and catch syntax errors.
JSON Formatter · SQL Formatter · Line ToolsEncode & Decode
Transform text and data between common encodings.
Base64 · URL Encoder · HTML EntitiesConvert Data & Files
Change image, document, and data formats locally.
JSON ↔ YAML · Image Converter · PDF to ImagesGenerate
Create identifiers, secrets, codes, and test data.
UUID · ULID · PasswordCompare
Find structural and line-level changes between inputs.
JSON Diff · Text DiffInspect
Examine patterns, metadata, headers, and values.
Regex Tester · Image Metadata · IP LookupTool index
Categories
74 working utilities, grouped by the data, file, or network task you are working with.
JSON & Data
Format, validate, compare, and convert structured data.
- JSON Formatter
- JSON5
- YAML
- JSON ↔ TOON
- Data Converter
- Data Model Generator
- Code Formatter
Encoding & Crypto
Encode values and calculate hashes in your browser.
- Base64
- URL Encoder
- Hash Generator
- JWT Decoder
- File Checksum
Image Tools
Compress, resize, convert, and inspect images locally.
- Image Compressor
- Image Resizer
- Image Converter
- HEIC Converter
- QR Scanner
PDF Tools
Merge, split, rotate, watermark, and extract PDF pages.
- PDF Merge
- PDF Split
- PDF Organizer
- PDF Watermark
- PDF to Images
- Images to PDF
Text Tools
Count, compare, transform, and test text.
- Regex Tester
- Word Counter
- Text Diff
- Case Converter
- Markdown Preview
- Markdown Formatter
- String Inspector
Date & Identifiers
Convert Unix time and generate browser-secure identifiers.
- Timestamp Converter
- UUID Generator
- Cron Generator
- ULID Generator
Generators
Generate passwords, UUIDs, and downloadable QR codes.
- Password Generator
- UUID Generator
- QR Code Generator
Network Tools
Inspect public IP data and calculate private IPv4 subnets.
- IP Lookup
- Subnet Calculator
Practical browser-tool guides
Choose a task, follow a working example, and check the result against the documented limits. Every guide links to a local browser tool. No account is required.
How to scan a QR code from an image or screenshot
Scan a QR screenshot on the same phone without uploading it. Follow the steps, try 12 downloadable images, and compare actual decode results and failures.
QR Code Scanner from Image →How to inspect an XML tree and its attributes online
Inspect XML attributes and repeated elements in a browser tree. Download three XML samples, compare exact JSON output, and check namespace and mixed-text limits.
XML Tree Viewer →How to generate TypeScript from JSON and review the result
Generate TypeScript from JSON, then check six actual input/output cases for missing fields, mixed arrays, nulls and large IDs. Includes downloadable examples.
JSON to TypeScript Generator →How to filter a JSON array and export selected fields
Follow a worked json query with jmespath workflow, troubleshoot common errors, and check the result before exporting.
JSON Query with JMESPath →How to convert local HTML to Markdown without loading remote resources
Follow a worked html to markdown converter workflow, troubleshoot common errors, and check the result before exporting.
HTML to Markdown Converter →How to optimize SVG and check the result before downloading
Follow a worked svg optimizer workflow, troubleshoot common errors, and check the result before exporting.
SVG Optimizer →How to generate reproducible JSON and CSV test data
Follow a worked mock data generator workflow, troubleshoot common errors, and check the result before exporting.
Mock Data Generator →How to create a ZIP and extract selected files in your browser
Follow a worked zip archive creator and extractor workflow, troubleshoot common errors, and check the result before exporting.
ZIP Archive Creator and Extractor →How to convert cURL to Fetch or Python and review conversion warnings
Follow a worked curl to javascript fetch and python requests workflow, troubleshoot common errors, and check the result before exporting.
cURL to JavaScript Fetch and Python Requests →How to validate JSON with a local Draft 7 schema
Follow a worked json schema validator workflow, troubleshoot common errors, and check the result before exporting.
JSON Schema Validator →How to generate and export a barcode locally
Follow a worked barcode generator workflow, troubleshoot common errors, and check the result before exporting.
Barcode Generator →How to convert CSS colors and check sRGB gamut
Follow a worked color converter workflow, troubleshoot common errors, and check the result before exporting.
Color Converter →How to query and export a local SQLite database
Follow a worked sqlite workspace workflow, troubleshoot common errors, and check the result before exporting.
SQLite Workspace →How to recognize English and Chinese text in a local image
Follow a worked image ocr — english & simplified chinese workflow, troubleshoot common errors, and check the result before exporting.
Image OCR — English & Simplified Chinese →How to convert a short local media file with browser-supported codecs
Follow a worked local audio & video converter workflow, troubleshoot common errors, and check the result before exporting.
Local Audio & Video Converter →