Code & Data
Decode Base64, and know when it is not text
Paste Base64 and get the text back. Line breaks, missing padding and the URL-safe alphabet are all accepted, and when the data decodes to something that is not text you are told rather than handed mojibake.
Whitespace and line breaks are ignored, and both the standard and URL-safe alphabets are accepted. Padding is optional.
Paste Base64 above and the decoded text appears here.
- Runs in your browser
- No account required
- Free to use
How it works
Whitespace is ignored, not rejected
Base64 arrives wrapped from email attachments and broken across lines when copied out of a terminal or a JSON file. Refusing those would fail on the commonest way people actually get Base64, so whitespace is stripped before decoding.
Both alphabets, padded or not
Standard + and / and URL-safe - and _ are accepted in the same pass, so you do not have to know which variant you were handed. Padding is optional, because JWTs and many APIs omit it.
Binary data is reported, not disguised
Decoding is done with a strict UTF-8 decoder. A lenient one replaces invalid bytes with question marks and hands back plausible-looking nonsense; this says the data is not text — which is the useful answer when someone has pasted an encoded image and expected words.
What it does
Errors that name the problem
An invalid character is quoted back to you. A length that could never have been produced by encoding is identified as such, rather than silently returning a truncated result.
Tolerant of real-world input
Wrapped lines, leading and trailing whitespace, missing padding and either alphabet all work without configuration.
Full Unicode support
Emoji, accents and non-Latin scripts decode correctly, because the bytes are decoded as UTF-8 rather than assumed to be Latin-1.
Your data never leaves the page
API responses, config files and exports are exactly the sort of thing that should not be pasted into someone else’s server. Parsing happens in your browser and what you paste is never transmitted — there is no code here that could send it anywhere, even by accident.
Practical advice
Getting a better result
- A JWT is three Base64 segments separated by dots. Decode them one at a time — the whole token is not a single Base64 string.
- If it decodes to binary, you probably have an encoded image or file rather than text. That is not an error in the data.
- Base64 is trivially reversible, so anything sensitive you decode here was never protected by the encoding in the first place.
Questions
Things people ask
Why does it say my Base64 is not text?
Because the bytes it decodes to are not valid UTF-8 — usually because the original data was an image, a compressed file or some other binary content rather than characters. The decoding worked; the result simply is not text.
Does it need the = padding?
No. Padding is optional here, because JWTs and many APIs omit it. What is rejected is a length that could not have been produced by encoding at all, which indicates the string has been truncated.
Can it decode a JWT?
It can decode each segment. A JWT is three URL-safe Base64 sections separated by dots, so paste the header or payload section on its own — the whole token is not one Base64 string.
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Open toolWho builds these
Free tools by day. Websites that earn their keep by trade.
KuConvert is built by KUDUY, a web design and development agency. From custom WordPress builds to SEO and e-commerce, everything they do is engineered to bring you more qualified traffic and turn it into revenue.
Web Design
Custom, conversion-focused web design that captivates visitors and turns them into paying customers. Mobile-first, fast, and built to rank.
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Custom WordPress websites built with clean code, blazing-fast performance (Core Web Vitals optimised), and enterprise-grade security.
E-Commerce
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SEO
Technical SEO, keyword research, on-page optimisation and local SEO strategies that drive qualified organic traffic.
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Data-driven campaigns that deliver measurable ROI across every channel.
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One-on-one expert support for bug fixes, updates and ongoing maintenance — without a long-term retainer.
Fixed scope, no surprise invoices
Most sites ship in four to eight weeks with the scope and the price agreed up front.
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Search is designed into the build — structure, schema and Core Web Vitals — not retrofitted.
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Need your whole site to load this fast?
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This tool runs entirely in your browser. Your files are never uploaded.