Base64 Encoder/Decoder
Encode text to Base64 or decode Base64 strings instantly in your browser. Free and private — data never leaves your device. No account needed.
What is Base64 Encoding?
Base64 encoding is a method of converting binary data into a plain ASCII text string using 64 printable characters — A-Z, a-z, 0-9, +, and /. It is used whenever binary data needs to travel through a system that only handles text — HTTP headers, JSON payloads, email attachments, and embedded images in HTML or CSS.
Base64 does not compress or encrypt data. The encoded output is roughly 33% larger than the original. Its only purpose is to make binary data safe to transmit as text without corruption.
How to Use the Base64 Encoder & Decoder
Paste your text or Base64 string
Paste the plain text you want to encode, or the Base64 string you want to decode, into the input field.
Choose Encode or Decode
Select Encode to convert plain text to a Base64 string, or Decode to convert a Base64 string back to plain text.
Copy the output
Click the copy button to copy the result to your clipboard.
Use in your code or request
Paste the result into your HTML data URI, HTTP Authorization header, API payload, or wherever it is needed.
Who Is This For?
- ▸ Developers embedding images in HTML or CSS as data URIs — encode the image file to Base64 and insert it directly into your code to eliminate an HTTP request.
- ▸ Backend engineers encoding credentials for HTTP Basic Auth headers — the Authorization header requires
username:passwordBase64-encoded before sending. - ▸ Anyone decoding a Base64 string received from an API — decode the value to inspect the raw content without writing a script.
Key Benefits
- ✓ Runs entirely in your browser — your data is never sent to a server, making it safe for API keys, JWT tokens, and Basic Auth credentials.
- ✓ Free with no subscription — no account, no paywall, no usage limits.
- ✓ No account required — open the page and start encoding immediately.
- ✓ Supports standard and URL-safe Base64 — encode in the correct variant for URLs, JWTs, or standard data transmission.
Common Uses for Base64
- Basic Authentication: HTTP Basic Auth requires headers formatted as
username:passwordand encoded in Base64. - Data URIs: Embedding small images or fonts directly into CSS or HTML files to reduce HTTP requests.
- Email Attachments: Email protocols (SMTP) were originally designed for text; attachments are often Base64 encoded to ensure safe delivery.
- JSON Web Tokens (JWT): JWTs consist of three parts (Header, Payload, Signature) that are Base64Url encoded.
Is Base64 Encryption?
No. Base64 is not encryption. It is simply a translation of data into a different format. Anyone with access to the Base64 string can instantly decode it back to the original text. Never use Base64 to secure or "encrypt" passwords or sensitive data at rest. For actual security, use cryptographic hashing (like bcrypt) or encryption algorithms (like AES).
URL-Safe Base64
Standard Base64 contains characters (+ and /) that have special meaning in URLs. When passing Base64 data in a URL query parameter or routing path, developers use a "URL-Safe" variant where + is replaced by - (dash) and / is replaced by _ (underscore). JWT tokens use this URL-safe variant.
Frequently Asked Questions
What is Base64 encoding?
Base64 is a method of encoding binary data as ASCII text using 64 printable characters — A-Z, a-z, 0-9, +, and /. It is commonly used to embed images in HTML or CSS, encode email attachments, and pass binary data through text-only systems like JSON or XML. Base64 does not compress data — the encoded output is roughly 33% larger than the original.
Is this tool free?
Yes — completely free with no account required. The Base64 encoder and decoder runs entirely in your browser. Your data is never sent to a server, making it safe for encoding API keys, credentials, and other sensitive content.
Why does Base64 end in == ?
Base64 encodes 3 bytes of input at a time into 4 characters of output. If the input length is not a multiple of 3, padding characters (= or ==) are added to complete the final 4-character group. One = means one byte of padding was needed; == means two bytes of padding were needed. This padding is required for correct decoding.
Is Base64 the same as encryption?
No. Base64 is encoding, not encryption. It is trivially reversible by anyone — there is no key or password involved. It only converts binary data into a text-safe format for transmission. Never use Base64 to secure passwords or sensitive data at rest. For actual security, use cryptographic hashing (like bcrypt) or encryption algorithms (like AES).
What is URL-safe Base64?
Standard Base64 uses + and / characters that have special meaning in URLs. URL-safe Base64 replaces + with - (hyphen) and / with _ (underscore), making the encoded string safe to include in a URL path or query parameter without additional percent-encoding. JWT tokens, for example, use URL-safe Base64.
Can Base64 encode binary files like images?
Yes. Base64 is most commonly used to encode binary files. When you embed an image in HTML or CSS as a data URI, the image file is Base64-encoded and inserted directly into the code — for example: src="data:image/png;base64,[encoded string]". This eliminates an HTTP request but increases the size of the HTML or CSS file.
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
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