64 tools · everything runs in your browser
Every tool you need,
without the upload.
Formatters, converters, calculators and image tools that work instantly and privately. No sign-up, no upload, no waiting.
Popular tools
The utilities people reach for most often.
JSON Formatter
Developer Tools
Format, beautify and validate JSON with 2 or 4 space indentation.
JWT Decoder
Developer Tools
Decode the header and payload of a JSON Web Token and inspect its claims.
UUID Generator
Developer Tools
Generate cryptographically random v4 UUIDs in bulk.
Base64 Encoder & Decoder
Developer Tools
Convert text to Base64 and back, with full Unicode support.
Unix Timestamp Converter
Developer Tools
Convert Unix timestamps to human dates and back, in UTC and local time.
Text Compare
Text Tools
Compare two texts and see every added, removed and changed line highlighted.
Word Counter
Text Tools
Count words, characters, sentences and paragraphs as you type.
Case Converter
Text Tools
Convert text between upper, lower, title, camel, snake and kebab case.
Browse by category
Nine collections covering development, design and everyday maths.
Developer Tools
Formatters, encoders, decoders and generators for everyday development work.
15 tools
Text Tools
Count, clean, sort and transform text without leaving your browser.
11 tools
Image Tools
Compress, resize, crop and convert images entirely on your device.
9 tools
PDF Tools
Merge, split, rotate and build PDFs — your files never leave your machine.
4 tools
CSS Tools
Visual generators that write modern CSS for you.
6 tools
Color Tools
Convert, inspect and check the accessibility of colors.
2 tools
Calculators
Everyday finance and maths calculators with transparent formulas.
6 tools
Converters
Fast, accurate unit conversion for length, weight, temperature and more.
7 tools
Date & Time
Work out ages, durations, working days and timestamps.
4 tools
Trending this month
Gaining the most use right now.
- JSON FormatterFormat, beautify and validate JSON with 2 or 4 space indentation.
- Regex TesterTest regular expressions live with highlighted matches and capture groups.
- Text CompareCompare two texts and see every added, removed and changed line highlighted.
- Case ConverterConvert text between upper, lower, title, camel, snake and kebab case.
- QR Code GeneratorCreate QR codes for links, Wi-Fi, contacts and text, then download PNG or SVG.
- Image CompressorShrink JPG, PNG and WebP files without leaving your browser.
Recently added
The newest additions to OnDevice Tools.
Free online tools that respect your privacy
OnDevice Tools is a collection of 64 browser-based utilities for developers, designers, writers and anyone who needs a quick answer. Every tool runs as JavaScript inside your own browser tab. There is no upload step, no queue and no account, because there is no server doing the work.
That design has three practical consequences. Results are instant, since nothing travels over the network. Your data stays private, whether it is a JWT from a staging environment, a contract you need to split, or a photo you would rather not hand to a stranger. And the whole site keeps working offline once you have visited it.
What you will find here
- Developer tools — JSON, XML, YAML and SQL formatters, Base64 and URL encoders, a JWT decoder, hash generation and a live regex tester.
- Text tools — word and character counting, case conversion, slug generation, line sorting and deduplication.
- Image and PDF tools — compression, resizing, cropping, format conversion, plus merging, splitting and rotating PDFs.
- CSS and colour tools — visual generators for shadows, gradients, grid and flexbox, colour conversion and WCAG contrast checking.
- Calculators and converters — percentages, EMI, SIP, GST, compound interest, plus unit conversion and date arithmetic.
Is it really free?
Yes — there is no paid tier, no usage limit and no sign-up. Because the work happens on your device rather than on rented servers, running OnDevice Tools costs very little, and advertising covers the rest. Ads are display slots on the page: they never see the file you opened or the result a tool produced, because that content is never sent anywhere.