Base64 Decoder — Base64 to Text
Decode any Base64 encoded string back to readable text instantly. Handles standard Base64 and URL-safe Base64 variants.
How to Decode Base64
- 1Paste the Base64 encoded string into the input
- 2The decoded text appears automatically
- 3If the input is invalid, an error message explains the issue
- 4Copy the decoded text with one click
Key Benefits
- Decodes standard and URL-safe Base64
- Clear error messages for invalid input
- Handles Unicode output correctly
- Instant decoding with no delay
Frequently Asked Questions
What characters are valid in Base64?
Standard Base64 uses A-Z, a-z, 0-9, + and /. URL-safe Base64 replaces + with - and / with _, making it safe for URLs without percent-encoding. Both variants pad the output with = so the total length is a multiple of 4. If you see - or _ in what looks like a Base64 string, it is likely the URL-safe variant — make sure to use a decoder that handles it.
Why does my Base64 show as invalid?
The most common causes: the string was truncated (copy-paste cut off characters), it contains spaces or newlines that broke the encoding, it uses characters outside the Base64 alphabet, or it was never Base64 in the first place. Some strings resemble Base64 but are actually hex-encoded hashes or other formats. Check the original source to confirm the data was actually Base64-encoded.
Can I decode binary files with this tool?
This tool decodes Base64 to text output. If the original data was binary (an image, PDF, font, or other file), the decoded result will display as garbled characters — the bytes are correct but cannot be meaningfully shown as text. To inspect a data URI, strip the prefix (data:image/png;base64,) and paste only the Base64 portion here.
How do I recognize a Base64-encoded string?
Base64 strings contain only alphanumeric characters, +, /, and optionally = padding at the end. Their length is always a multiple of 4 (before removing URL-safe padding). One or two trailing = signs are a strong indicator of Base64. Strings containing characters outside this set — like %, #, or spaces — are not valid Base64.
What is the relationship between Base64 and data URLs?
Data URLs embed resource content directly in HTML or CSS using the format data:[media type];base64,[Base64 string]. For example, a small PNG can be inlined as data:image/png;base64,iVBOR... This removes the need for a separate HTTP request but increases the size of the HTML or CSS file. To inspect what a data URL contains, strip the prefix and paste the Base64 portion here.
Why does decoded text look garbled or show random symbols?
This usually means the original data was binary — an image, PDF, or other file — not text. Base64 can encode any binary data, but displaying binary bytes as text produces meaningless characters. A second possible cause is a character encoding mismatch: if the original text was encoded in Latin-1 or another non-UTF-8 encoding, some characters may not convert correctly.