JsonifyTools
    Live Encoding · 100% Local · Zero Upload

    Base64 Encoder

    The most complete Base64 tool — text, files, multi-level, URL-safe and MIME — all processed privately in your browser.

    Everything processed locally No data ever uploaded
    Levels
    1
    Input
    1234567891011121314
    OutputBase64
    1234567891011
    Encoding Reference

    Everything You Need to Know About Base64

    From API headers to JWT tokens to file embedding — Base64 is everywhere in modern development. Here's how it works, when to use it, and how this tool covers every scenario.

    Live Encoding

    Output updates instantly as you type — no button click required.

    100% Client-Side

    Nothing is uploaded. All encoding runs in your browser sandbox.

    3 Variants

    Standard, URL-Safe (JWT-ready), and MIME (RFC 2045) in one tool.

    File Support

    Encode images, PDFs, and binary files directly — no CLI required.

    What is Base64 Encoding?

    Base64 is a binary-to-text encoding scheme that converts arbitrary binary data into a sequence of 64 printable ASCII characters. It was designed to safely transport binary content — like images, certificates, or files — through channels that only support text, such as email (SMTP), HTTP headers, and JSON payloads.

    The algorithm processes input in 3-byte chunks and maps each group to 4 Base64 characters. If the input length isn't divisible by 3, = padding characters are appended. This results in output that is approximately 33% larger than the original binary data.

    The Base64 Alphabet

    Base64 uses exactly 64 characters to represent 6-bit binary values (2⁶ = 64). The standard alphabet is:

    Base64 character set
    A–Z  →  indices 0–25   (uppercase)
a–z  →  indices 26–51  (lowercase)
0–9  →  indices 52–61  (digits)
+    →  index 62       (standard)
/    →  index 63       (standard)
=    →  padding only   (not a value)

URL-Safe variant:
+  →  -   (safe in URLs)
/  →  _   (safe in URLs)
    Live Examples

    Base64 encoding examples — copy & try

    Select any example below, copy the input or output, and paste it into the encoder above to verify.

    Input (Plain Text)
    Hello, World!
    Base64 Output
    SGVsbG8sIFdvcmxkIQ==

    💡 Standard Base64 encoding. Note the == padding at the end.

    Standard vs URL-Safe vs MIME — Which Variant to Use?

    Choosing the wrong Base64 variant is a common source of bugs. Here's when to use each one.

    VariantSpecial CharsBest ForRFC
    Standard+ / =General data encoding, email attachments, JSON payloadsRFC 4648 §4
    URL-Safe- _ =JWT tokens, OAuth params, query strings, cookie values, filenamesRFC 4648 §5
    MIME+ / = + line breaksEmail body/attachments, S/MIME, PEM certificatesRFC 2045

    How to use this Base64 Encoder & Decoder

    1

    Encode Text

    Type or paste any text in the input panel. The Base64 output updates live. Switch variants (Standard / URL-Safe / MIME) from the toolbar.

    2

    Decode Base64

    Paste a Base64 string — the tool auto-detects if you are encoding or decoding based on the content. The decoded plain text appears instantly in the output.

    3

    Encode Files

    Click the File tab to drag & drop or select any binary file (image, PDF, audio). The encoder reads it as binary and produces a complete Base64 data string.

    4

    Multi-Level

    Use the Level selector to encode 2× or 3× in sequence — useful for QA testing decoders, verifying multi-pass pipelines, or security research.

    Where Base64 is Used
    • JWT tokens — header and payload sections are Base64URL encoded
    • HTTP Basic Auth — credentials encoded as Base64 in the Authorization header
    • Email attachments — MIME Base64 embeds binary files in SMTP messages
    • Data URIs — images and fonts embedded inline in HTML and CSS
    • API payloads — binary data safely transported in JSON string fields
    • OAuth / OIDC — tokens, code challenges, and state parameters
    • TLS certificates — PEM files use Base64 to encode X.509 DER data
    • Webhooks — binary webhook payloads encoded for HTTP transport
    Tool Features
    • Live encoding / decoding — output updates as you type
    • Standard, URL-Safe, and MIME Base64 variants
    • Multi-level encoding (1×, 2×, 3×) for pipeline testing
    • File tab — encode any binary file (images, PDFs, audio)
    • Payload size stats — input bytes, output length, overhead %
    • Copy to clipboard and download output in one click
    • 100% browser-based — no data leaves your device
    • Free, no account required, no usage limits
    Base64 is NOT Encryption — Important Distinction

    A very common misconception is that Base64-encoding data makes it secure or secret. It does not. Base64 is a reversible encoding scheme — any person or system with the encoded string can decode it back to the original plaintext instantly, without any password or key.

    If you need to protect sensitive data, use proper cryptographic mechanisms:

    Symmetric Encryption

    AES-256-GCM for encrypting data at rest or in transit with a shared secret key.

    Asymmetric Encryption

    RSA or ECDSA for public/private key scenarios like TLS, signing, and key exchange.

    Hashing

    SHA-256, bcrypt, or Argon2 for storing passwords and verifying data integrity.

    💡 Base64 is safe for encoding API keys in Authorization headers only because HTTPS encrypts the transport layer — not because Base64 itself provides security.

    Data URI Example

    Embedding Images as Base64 Data URIs

    Data URIs let you embed binary files directly in HTML and CSS without external requests. The format is data:[type];base64,[encoded]. This is common for small icons, inline fonts, and email images.

    data-uri-example.htmlHTML
    <!-- PNG image embedded as a data URI -->
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4
BCATAAAABQABIwIRAU..." alt="icon" />

<!-- CSS background image as data URI -->
<style>
  .logo {
    background-image: url('data:image/svg+xml;base64,
      PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAw...');
  }
</style>

    Use the File tab in the encoder above to convert any image to a Base64 string, then wrap it in the data:[type];base64, prefix to create a data URI.

    Decoding JWT Tokens with Base64URL

    JSON Web Tokens (JWT) are composed of three Base64URL-encoded sections separated by dots: header.payload.signature. The header and payload are just Base64URL-encoded JSON — you can decode them instantly with this tool.

    JWT decode steps
    // Example JWT (abbreviated)
eyJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJ1c2VyXzEyMyIsInJvbGUiOiJhZG1pbiJ9.sig

// Step 1: Split by "."
Header:    eyJhbGciOiJSUzI1NiJ9
Payload:   eyJzdWIiOiJ1c2VyXzEyMyIsInJvbGUiOiJhZG1pbiJ9
Signature: sig (binary — cannot be decoded to readable text)

// Step 2: Switch to URL-Safe variant in the tool
// Step 3: Paste the Header segment → decoded JSON:
{ "alg": "RS256" }

// Step 4: Paste the Payload segment → decoded JSON:
{ "sub": "user_123", "role": "admin" }

    ⚠️ Never verify JWT authenticity by just decoding the payload — always validate the signature server-side using the correct public key.

    Complete Feature Set

    Everything a developer needs to work with Base64 — in one free, browser-based tool.

    Live Encoding & Decoding

    Output refreshes with every keystroke. No submit button. No waiting.

    Auto Detect Mode

    Automatically identifies if your input is raw text or a Base64 string and switches mode accordingly.

    Binary File Encoding

    Encode images, PDFs, audio, and any binary file to Base64 using the File tab — handles large files without blocking the UI.

    Download Output

    Export the encoded or decoded result as a file to your local file system with one click.

    Multi-Level Encoding

    Encode up to 3× in sequence. Useful for QA, security testing, and verifying multi-pass decode pipelines.

    URL-Safe Output

    Switch to URL-Safe variant for JWT, OAuth, and query string use — no percent-encoding needed.

    Frequently Asked Questions

    Common questions about Base64 encoding, decoding, and when to use each variant.