Base64 Encoder & Decoder

Encode and decode Base64 strings instantly. Free online Base64 converter tool for text and files. Works entirely in your browser.

Last updated: June 1, 2026

Text to Encode

Result

What is Base64 Encoder/Decoder?

Base64 is a binary-to-text encoding scheme that converts binary data into a sequence of printable ASCII characters. It uses a set of 64 characters (A-Z, a-z, 0-9, +, and /) to represent data, with '=' used for padding. Base64 encoding is essential in web development because many protocols and formats (email, HTML, CSS, JSON) only support text. When you need to embed an image in CSS, send binary data through a JSON API, include an attachment in an email, or store binary data in a text-based database field, Base64 encoding makes it possible. This tool lets you encode text or data to Base64, and decode Base64 strings back to their original form.

How It Works

To encode, paste your text or data into the input field and the tool converts each group of 3 bytes into 4 Base64 characters using the standard Base64 alphabet. The encoding process takes the binary representation of your input, splits it into 6-bit chunks, and maps each chunk to one of 64 characters. To decode, paste a Base64 string and the tool reverses the process — converting each group of 4 characters back to 3 bytes of original data. The tool auto-detects whether your input is already Base64-encoded and suggests the appropriate operation. All processing runs in your browser using the built-in btoa() and atob() functions.

Examples

Text to Base64 encoding

Input

Hello, World!

Output

SGVsbG8sIFdvcmxkIQ==

Base64 to text decoding

Input

V2ViVG9vbHNPbmxpbmU=

Output

WebToolsOnline

Tips & Best Practices

💡

Base64 encoding increases data size by exactly 33% (4 output bytes for every 3 input bytes). Factor this into storage and bandwidth calculations.

💡

Data URIs (data:image/png;base64,...) let you embed small images directly in CSS/HTML, eliminating an HTTP request at the cost of larger file size.

💡

Base64 is encoding, not encryption. Anyone can decode it — never use it to protect sensitive data.

Common Use Cases

•Embedding small images directly in HTML or CSS as data URIs to reduce HTTP requests
•Encoding API authentication credentials for HTTP Basic Auth headers
•Sending binary file data through JSON APIs that only accept text strings
•Encoding email attachments for SMTP transmission via MIME format
•Storing binary data in text-based configuration files like XML or YAML
•Decoding Base64 strings from API responses to inspect the original data content

Frequently Asked Questions

What is Base64 encoding?▼

Base64 is a binary-to-text encoding scheme that converts binary data into an ASCII string format using 64 printable characters (A-Z, a-z, 0-9, +, /). It's used to safely transmit binary data through text-only channels.

When should I use Base64?▼

Common uses include embedding images in HTML/CSS, encoding data for APIs, email attachments (MIME), storing binary data in text-based formats, and HTTP Basic Auth headers. It's essential whenever binary data needs to pass through text-only protocols.

Is there a size limit?▼

Since all processing happens in your browser, the limit depends on your device's memory. Most texts up to several MB work fine. Note that Base64 encoding increases data size by approximately 33%.

Why does Base64 make data larger?▼

Base64 represents 3 bytes of data using 4 characters. This 4/3 ratio means encoded data is always about 33% larger than the original. This trade-off is acceptable because it ensures compatibility with text-only systems.

Is Base64 encryption?▼

No. Base64 is encoding, not encryption. It provides no security — anyone can decode a Base64 string. It's used for data format compatibility, not confidentiality. For security, use actual encryption algorithms.

What's the difference between Base64 and URL-safe Base64?▼

Standard Base64 uses + and / characters which have special meaning in URLs. URL-safe Base64 replaces these with - and _ so the encoded string can be safely used in URLs and filenames without percent-encoding.