Base64 encoder and decoder
Convert text or a local file to Base64 and back, without uploads.
Files stay on your device. Nothing is uploaded.
One local file, up to 10 MiB. For Decode, choose a file containing Base64 text.
Binary result: download the exact bytes. No readable UTF-8 preview is available.
Preview limited to 16,384 characters. Copy and Download include the full result.
Input: text up to 1 MiB (1,048,576 UTF-8 bytes), or one file up to 10 MiB (10,485,760 bytes), in either direction.
Base64 is not encryption. Input and output stay in memory; nothing is uploaded, saved or put in the page URL.
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Turn text or a file into Base64, or recover the original bytes from an encoded value. Use it to inspect an API field, prepare a small attachment, or read a payload copied from a development tool. Text uses UTF-8, so accents, emoji and non-Latin scripts survive the conversion. Choose the standard or URL-safe alphabet to match the system you are working with. Processing stays in your browser, and the page does not save your input.
How to use
- Choose Encode or Decode, then select Text or File as the source.
- Paste a value, or choose one local file and press Run. Text converts as you type.
- Select URL-safe when your data uses - and _; enable wrapping only when encoding.
- Copy the complete text result or download the output. Use Clear to remove the current input.
What it handles
- UTF-8 text preserves combining marks, emoji and original line endings.
- URL-safe output omits padding; standard output includes required = characters.
- Wrapping inserts CRLF line breaks every 76 characters, without a trailing break.
- Invalid alphabet, padding and nonzero unused bits produce an error.
- Binary output downloads as exact bytes; it is never forced into replacement text.
FAQ
Is Base64 encryption?
No. Base64 represents bytes using a limited alphabet; anyone who has the encoded value can decode it. It provides no secrecy, password protection or authenticity check. Do not treat an encoded credential as hidden, and do not assume a successfully decoded file is safe to open.
What are the text and file limits?
Each input is limited to 1 MiB of UTF-8 text (1,048,576 bytes) or one 10 MiB file (10,485,760 bytes), in either direction. Base64 increases size by roughly one third. A maximum-sized encoded result can therefore exceed the input limit for a later decode. Use smaller inputs when a round trip is needed.
Why is there no readable text after decoding?
A valid Base64 value can contain an image, archive or other binary data. When bytes are not valid UTF-8, or contain nonprinting controls, the tool offers a binary download instead of inventing readable characters. Base64 carries no reliable filename or type information, so identify the format before opening the downloaded file.
Which spaces and padding does the decoder accept?
The decoder ignores ordinary ASCII spaces, tabs, carriage returns and line feeds. Correct padding may be present or omitted. Other characters, mixed alphabets, misplaced equals signs and nonzero unused bits are rejected. Remove a data URL prefix first; paste only the Base64 part, without percent escapes.
Is the preview the complete result?
The preview shows up to 16,384 characters to keep the page responsive. Copy and Download use the full result, including text beyond that preview. Neither input nor output is saved to browser storage or added to the page address. Clear and Cancel invalidate pending work so an older result cannot reappear.
Updated