Free online converters do one job well: they take data in one format and hand it back in another. Convert a binary string into readable text, a BMP photo into a PNG, a Base64 blob into an image, a column of JSON into a CSV row. Each is a small, exact task that is slow and error-prone by hand and instant with the right tool. This guide is a map of the converters on this site, grouped by what they convert, so you can find the one you need and understand what it actually does.
In this guide
What an online converter does
A converter reads data in a source format and writes it out in a target format, without changing the underlying meaning. The number stays the same number, the image stays the same image, only the way it is written changes. That sounds simple, but every format has its own rules, and applying them by hand is where mistakes creep in.
The converters here all run in your browser. The data is processed on your own device and is not uploaded to a server, which matters when you are converting something private. None of them need an account, and there is no install. You paste or upload, you get the result.
Number system converters
Number system converters move a value between binary, decimal, hexadecimal, and octal. These are the most searched conversions in computing, because programmers meet all four systems daily. The binary to decimal converter turns a binary string into the everyday numbers people read, and the binary to hex converter packs it into the compact hex form used for colours and memory.
The binary to octal converter handles the base-8 form still used in Unix file permissions. The full set lives in the binary tools category and the number tools category.
Text and character converters
Text converters move between human-readable characters and the codes a computer stores them as. The binary to text converter turns a binary string back into words, and the text to binary converter does the reverse, which is the pair people search for most.
From there the character converters fan out. The ASCII to hex converter shows text as hex character codes, and for something different, the text to Morse code converter turns a message into dots and dashes. These and more sit in the text tools category.
Base64 and data converters
Base64 is the format that lets binary data travel as plain text, so converting to and from it is a constant need. The Base64 to image converter turns a Base64 string back into a viewable picture, and the Base64 to PDF converter does the same for documents.
For structured data, the Base64 to JSON converter decodes an encoded payload back into readable JSON, the form it usually started as before it was wrapped for transport.
Image format converters
Image converters change a picture from one file format to another while keeping the image itself unchanged. The strongest set here is built around BMP, the large uncompressed format that almost always needs converting to something smaller before sharing.
The BMP to PNG converter produces a lossless, much smaller file, and the BMP to JPG converter produces an even smaller one for photos where some quality loss is fine. The wider set is in the image tools category.
Data format converters
Data converters reshape structured data between the formats applications expect. The BSON to JSON converter turns the binary form used by databases such as MongoDB into readable JSON, and the CSV delimiter converter swaps the separator in a CSV file, the usual fix when a file made with semicolons will not open correctly. These live in the JSON tools category and the CSV tools category.
Choosing the right converter
Two questions point you to the right tool. First, what do you have, and what do you need it to become? That is the source and target pair, and it names the converter directly: a BMP you need as a PNG means the BMP to PNG converter. Second, does the conversion lose anything? Some conversions are lossless and reversible, such as binary to decimal. Others, like converting a photo to JPG, trade a little quality for a smaller file. Knowing which kind you are doing tells you whether you can convert back later without harm.
Popular free converters
Frequently asked questions
Are these converters free?
Yes. Every converter on the site is free, runs in your browser, and needs no account. The data is processed on your own device.
Is my data uploaded when I convert it?
No. The converters process data in your browser, so the file or text stays on your device rather than being sent to a server.
What is the difference between a lossless and a lossy conversion?
A lossless conversion keeps all the original data and can be reversed exactly, such as binary to decimal. A lossy conversion drops some detail for a smaller file, such as converting a photo to JPG.
Why will my CSV not open correctly?
It most likely uses a different separator than your software expects, often a semicolon instead of a comma. A CSV delimiter converter fixes it.
Can I convert a Base64 string back into a file?
Yes. A Base64 to image or Base64 to PDF converter decodes the string back into the original file you can view or save.