Guide
Base64 Decoder — complete guide
What is a Base64 Decoder?
A Base64 decoder reverses Base64 text back into the original bytes or characters. Developers decode Base64 when inspecting JWT segments, reading data URIs, debugging email MIME parts, or unpacking values stored in JSON fields.
space4.dev decodes Base64 entirely in the browser so sensitive strings stay on your machine.
How to decode Base64 online
Workflow:
- Paste a Base64 string (with or without whitespace).
- Decode to reveal the underlying text.
- If decoding fails, check for missing padding, URL-safe alphabet mix-ups, or truncated input.
- For images stored as Base64, use the Base64 Image Decoder instead of the text decoder.
Base64 is not encryption
Never assume a Base64 string hides secrets. It is an encoding, not a cipher. Anyone with this decoder (or openssl, or Python) can reverse it. Use proper encryption and hashing for confidentiality.