To convert Base64 to JSON, you decode the Base64 text back into the structured data it was wrapped from. Base64 is often used to carry a JSON payload, a CSV file, or raw bytes through systems that only handle plain text, and the result is an unreadable string until you decode it. This guide shows how to convert Base64 to JSON, CSV, hex, and plain text, with a free tool for each, and what to check when the decoded result still does not look right.
In this guide
Base64 as a wrapper around data
Base64 does not change what data is, only how it is written. A JSON object, a CSV table, or a block of bytes gets rewritten as a single text string so it can ride safely inside an API response, a token, or a database field. To use that data again, you decode it back to its original form. The background on the encoding itself is in our guide to Base64 encoding.
The converters below each assume a different thing is hiding inside the string, and they decode it accordingly.
Convert Base64 to JSON
This is the most common case for developers. API payloads, configuration, and the body of a JWT token are frequently JSON wrapped in Base64. The Base64 to JSON converter decodes the string and returns the JSON, ready to read or validate.
A quick signal: a Base64 string that begins with the characters eyJ is almost always JSON, because that is how an opening brace and quote encode. It is exactly why JWT tokens start that way. If yours starts with eyJ, expect JSON on the other side. To then check the structure, our guide to JSON and CSV tools covers the analyzer.
Convert Base64 to CSV
Tabular data is also carried this way, often when a spreadsheet export is attached to a request or stored as a single field. The Base64 to CSV converter decodes the string back into rows and columns you can open in a spreadsheet program.
Convert Base64 to hex
Sometimes you need the underlying bytes rather than a guessed format. The Base64 to hex converter shows the decoded data as hexadecimal, two characters per byte. This is the tool to reach for when you are inspecting unknown data and want to see its raw bytes, since hex reveals file signatures and structure that text would hide.
Convert Base64 to plain text
When the data is simply text, two converters return it directly. The Base64 to UTF-8 converter handles modern text with accents, other alphabets, and symbols, while the Base64 to ASCII converter is fine for plain English. If your decoded text shows odd characters where accents should be, switch to the UTF-8 tool.
Decoded but still unreadable
If a string decodes without error but the result is still gibberish, the data was probably not plain text or JSON to begin with. The most common reasons are that it was compressed before encoding, or encrypted, in which case decoding Base64 only removes the outer text wrapper and leaves the compressed or encrypted bytes underneath. Viewing it as hex often makes this clear, since a recognisable file signature at the start tells you what the real format is.
Free Base64 converters used in this guide
Frequently asked questions
How do I convert Base64 to JSON?
Paste the string into a Base64 to JSON converter. It decodes the text and returns the JSON it was wrapped from, ready to read or validate.
Why does my Base64 string start with eyJ?
Because eyJ is how an opening brace and quote encode in Base64, so a string starting with it is almost always JSON. JWT tokens start this way for the same reason.
What if the decoded data is still unreadable?
The data was likely compressed or encrypted before encoding. Decoding Base64 removes only the text wrapper, leaving those bytes underneath. Viewing it as hex helps identify the real format.
Should I use the ASCII or UTF-8 converter?
Use UTF-8 for text with accents, other alphabets, or symbols. ASCII is fine for plain English. If accents look wrong, switch to UTF-8.
Is decoding Base64 reversible?
Yes. Base64 is a lossless wrapper, so the decoded data is exactly what was encoded, with nothing added or removed.