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Base64 Encode / Decode

Convert text and files to/from Base64 encoding

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What is Base64 Encode/Decode?

Free Base64 encoder and decoder. Convert text or files to Base64 encoding and decode Base64 strings back to plain text instantly. Developer utilities built for web developers, software engineers, and programmers. TekPulse's Base64 Encode/Decode is completely free — no signup, no ads in results, and no data stored on our servers.

How to Use Base64 Encode/Decode Online

  1. Paste your text or binary data into the input area
  2. Click "Encode" to convert to Base64, or "Decode" to convert from Base64 to original
  3. Use the File tab to encode or decode files directly — the output is a Base64 data URI
  4. Copy the result to clipboard with one click
  5. Base64 is commonly used for embedding images in CSS/HTML and for API authentication tokens

Base64 Encode/Decode Formula & Calculation

Base64 groups input into 3-byte (24-bit) blocks → splits each into four 6-bit values → maps each to one of 64 symbols (A–Z, a–z, 0–9, +, /)

Each 6-bit value (0–63) is looked up in the Base64 alphabet, so every 3 bytes of input become exactly 4 output characters — a 33% size increase. If the input length isn't a multiple of 3, the last block is padded with 1 or 2 '=' characters to keep the output length a multiple of 4.

Example: the text "Hi!" is the bytes 72, 105, 33 (01001000 01101001 00100001). Regrouped into 6-bit chunks: 010010 000110 100100 100001 → decimal 18, 6, 36, 33 → alphabet lookup → "SGkh". This tool uses encodeURIComponent/decodeURIComponent around atob/btoa so multi-byte UTF-8 characters (emoji, non-Latin scripts) round-trip correctly instead of corrupting.

Key Factors That Affect Your Result

  1. Output size — Base64 output is always ~33% larger than the original binary/text, since 3 bytes become 4 characters. Don't use it for large files where bandwidth matters — it's for safely embedding binary data in text contexts (JSON, URLs, email), not compression.
  2. Padding (=) — Appears when input length isn't divisible by 3. One '=' means the last block had 2 bytes, two '=' means it had 1 byte. Some URL-safe variants (JWT, for example) strip padding entirely and use '-'/'_' instead of '+'/'/'.
  3. Not encryption — Base64 is an encoding, not a cipher. Anyone can decode it instantly with no key — never use it to "hide" sensitive data like passwords or API keys.

Why Use TekPulse Base64 Encode/Decode?

Runs Entirely in Your Browser
Encoding and decoding use native btoa/atob — your text and files never leave your device
Encode & Decode Text
Convert plain text to Base64 and back, with full UTF-8 support
URL-Safe Base64 Option
Swap +/ characters for -_ and strip padding for safe use in URLs and filenames
File to Base64
Convert any file such as an image or PDF to a Base64 data URI using the browser's FileReader

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How Base64 Encoding Actually Works

Frequently Asked Questions

Base64 encodes binary data into ASCII text using 64 printable characters (A-Z, a-z, 0-9, +, /). It increases size by ~33% but allows binary data to be safely transmitted over text-based protocols like email or JSON.

Base64 is used for: embedding images in HTML/CSS (data URIs), encoding email attachments (MIME), storing binary data in JSON, HTTP Basic Authentication, and transmitting binary data through text-only APIs.

No. Base64 is encoding, not encryption. It is easily reversible by anyone — it provides no security. Do not use Base64 to hide sensitive data. Use proper encryption (AES, RSA) for security.

Use our tool: upload or paste the image, and it converts to a Base64 data URI string like: data:image/png;base64,iVBORw0KGgo... This can be embedded directly in HTML img src or CSS background-image.

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