What is Base64 Encoder & Decoder Online?
Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format using 64 printable characters (A–Z, a–z, 0–9, +, /). It is the standard for embedding binary data in text-only contexts like JSON, HTML data URIs, email attachments (MIME), and API payloads. URL-safe Base64 replaces `+` with `-` and `/` with `_` to prevent encoding conflicts in query strings. This tool auto-detects which variant to use.
How to Use Base64 Encoder & Decoder Online
- Paste your plain text into the left input.
- The Base64 encoded output appears instantly in the right panel.
- Toggle to "Decode" mode to reverse-engineer a Base64 string.
- Click Copy to capture the result.
Example
Base64 encoding of "Hello, World!"
Input
Hello, World!Output
SGVsbG8sIFdvcmxkIQ==Developer Tips
When working with Base64 encoder online tools, remember that Base64 is ideal for binary-to-text conversion but not for storage optimization. In Node.js, you can convert a string to Base64 using `Buffer.from(str).toString('base64')`. For browser-based JavaScript, use `btoa(str)` for encoding and `atob(str)` for decoding, but be careful with UTF-8 characters as those APIs only support Latin1.
Frequently Asked Questions
Is Base64 encryption?
No. Base64 is encoding, not encryption. It is trivially reversible and provides zero security. Never use Base64 to "hide" sensitive data.
Why do Base64 strings end with == or =?
Base64 encodes 3 bytes at a time into 4 characters. When input length is not a multiple of 3, padding characters (=) are added to complete the last group.
What is URL-safe Base64?
Standard Base64 includes + and / which conflict with URL syntax. URL-safe Base64 replaces them with - and _ so the result can be safely embedded in query parameters.
What is the size overhead of Base64?
Base64 increases data size by approximately 33%. Every 3 bytes of input produce 4 bytes of Base64 output.