21 free tools that run in your browser
No signup. No uploads. No tracking. Everything happens on your own device.
Utilities that run on your device, not on a server
Pasting a production JWT, a customer list or a client's contract into a random website means handing that data to whoever runs it. Every tool here avoids the question entirely: the page loads once, and from then on the formatting, decoding, hashing, resizing and arithmetic all happen in your own browser. Disconnect from the internet and the tools keep working — that is the simplest proof that nothing is being uploaded.
There are no accounts, no per-day limits and no paywalled features. Web Toolkit is built and maintained by Ikonode as a single, growing collection rather than 21 separate landing pages, so the tool you need next is one keystroke away: press ⌘K anywhere on the site to search all of them.
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Format, decode and inspect the data formats you work with every day — plus the generators that go with them.
View all 11 →These tools are needed at the worst possible moment: a webhook payload arrives on one unreadable line, a token has to be checked before a deploy goes out, a config file will not parse and the error message points at "line 1".
In this category:JSON FormatterJWT DecoderQR Code GeneratorRegex TesterBase64 Encoder / DecoderCron Expression ParserSQL FormatterYAML FormatterHash GeneratorURL Encoder / DecoderUUID Generator
Writing for the web means writing to limits. A meta description that runs past roughly 160 characters gets truncated in search results, a title past about 60 characters does the same, and an ad headline or a social post has a hard cap. Counting by eye does not work, and counting in a word processor gives you the wrong number because it disagrees about what a character is.
In this category:Text Case ConverterText Diff CheckerWord Counter
The arithmetic here is not hard, which is precisely why it goes wrong. Percentage change and percentage difference are not the same calculation and answer different questions. A "20% discount then 20% off" is not 40%. Return on investment quoted without a time period cannot be compared to anything. Compound growth is the one people underestimate most, because the intuition is linear and the maths is not.
In this category:Compound Interest CalculatorROI CalculatorPercentage Calculator
Dates are where confident code breaks. A Unix timestamp in a log is seconds, the one in your JavaScript is milliseconds, and reading one as the other puts you in 1970 or the year 56000. Counting days between two dates by hand fails at month boundaries, leap years and the two days a year when daylight saving time makes a "day" 23 or 25 hours long.
In this category:Unix Timestamp ConverterDate Difference Calculator
Image tools are the ones most worth being careful about, because "upload your photo to resize it" means giving a stranger the original file and whatever metadata it carries. These two do the work with the Canvas API inside your browser: the file is read from disk by the page, processed in memory, and handed back as a download. Nothing is transmitted, which you can verify by going offline before you start.
In this category:Image ConverterImage Resizer