Does this tool work entirely in my browser?

Yes. Encoding and decoding both use built-in browser APIs (btoa/atob plus a small UTF-8 wrapper). Nothing is uploaded — your input, including sensitive content like JWTs, API keys, or Basic Auth credentials, never leaves your device. No logging, no analytics on the content.

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

Standard Base64 (RFC 4648 §4) uses A-Z, a-z, 0-9, +, /, and = for padding. URL-safe Base64url (RFC 4648 §5) substitutes - for + and _ for / so the result is safe inside URLs without further encoding, and typically omits the = padding. JWTs, OAuth tokens, and many web standards use the URL-safe variant.

Can this tool encode files or images?

No. This tool is text-only. To convert an image or binary file to a Base64 data URI, paste a small script into your browser's DevTools console — for example: `const b = await file.arrayBuffer(); const s = btoa(String.fromCharCode(...new Uint8Array(b))); console.log('data:image/png;base64,' + s);` — or use a command-line tool like `base64 < file.png`. The text input here accepts UTF-8 text up to several MB but will not parse binary file content.

Why does my decoded Base64 look like garbled characters?

If the original encoded content was binary (an image, PDF, executable, or other non-text data), the decoded output cannot be displayed as readable text — you're seeing UTF-8 attempting to interpret raw bytes. This usually means the source isn't text to begin with, not that decoding failed. To recover the actual binary file, you'd need a binary-aware tool.

Why is my JWT failing to decode?

Two common reasons: (1) you pasted only part of the JWT — make sure you're decoding ONE segment at a time (split the token on the dots), not the whole thing. (2) JWTs use URL-safe Base64 — switch the mode toggle to URL-safe and try again. For full JWT inspection with signature verification, use our dedicated JWT Decoder.

Is Base64 a form of encryption or compression?

Neither. Base64 is an encoding — a deterministic, reversible mapping that lets binary data travel safely through text-only channels (JSON, XML, HTTP headers, email). It does not protect content from being read (encoding ≠ encryption) and it actually makes data larger, not smaller (encoding ≠ compression).

Why is the Base64 output longer than the input?

Base64 uses 6 bits per character to represent 8-bit binary, so every 3 input bytes produce 4 output characters — about a 33% increase. There's no way to avoid this overhead with Base64; if size matters and the channel allows binary, send the raw bytes instead.

What's a Base64 data URI?

A data URI embeds content directly in a URL using the syntax data:[mime-type];base64, . Example: data:image/png;base64,iVBORw0KGgo... You can use this in CSS (background-image), HTML (img src), or anywhere a URL is expected. Best for tiny assets — larger ones bloat HTML/CSS files and hurt cache efficiency.

Can I decode a Base64 string that was copied with extra newlines?

Yes. The tool ignores whitespace inside the input — line breaks, spaces, and tabs are stripped before decoding. PEM-style content (which wraps at 64-76 chars per line) and shell-copied output paste cleanly.

Why does the "likely Base64" indicator say No on valid text?

The detector checks both the character set (only Base64 alphabet allowed, plus padding) and the length (a multiple of 4 for standard Base64). Plain English text usually contains characters outside the Base64 alphabet (spaces, punctuation, etc.) and so is correctly flagged as not-Base64. This is a feature — it prevents the decoder from trying to interpret arbitrary text as Base64 and producing nonsense.

KonverterTeil von Konverter →

Base64 Encoder / Decoder

Q: Why does my decoded Base64 look like garbled characters?

If the original encoded content was binary (an image, PDF, executable, or other non-text data), the decoded output cannot be displayed as readable text — you're seeing UTF-8 attempting to interpret raw bytes. This usually means the source isn't text to begin with, not that decoding failed. To recover the actual binary file, you'd need a binary-aware tool.

Q: Why is my JWT failing to decode?

Two common reasons: (1) you pasted only part of the JWT — make sure you're decoding ONE segment at a time (split the token on the dots), not the whole thing. (2) JWTs use URL-safe Base64 — switch the mode toggle to URL-safe and try again. For full JWT inspection with signature verification, use our dedicated JWT Decoder.

Q: Is Base64 a form of encryption or compression?

Neither. Base64 is an encoding — a deterministic, reversible mapping that lets binary data travel safely through text-only channels (JSON, XML, HTTP headers, email). It does not protect content from being read (encoding ≠ encryption) and it actually makes data larger, not smaller (encoding ≠ compression).

Q: Why is the Base64 output longer than the input?

Base64 uses 6 bits per character to represent 8-bit binary, so every 3 input bytes produce 4 output characters — about a 33% increase. There's no way to avoid this overhead with Base64; if size matters and the channel allows binary, send the raw bytes instead.

Q: What's a Base64 data URI?

A data URI embeds content directly in a URL using the syntax data:[mime-type];base64, . Example: data:image/png;base64,iVBORw0KGgo... You can use this in CSS (background-image), HTML (img src), or anywhere a URL is expected. Best for tiny assets — larger ones bloat HTML/CSS files and hurt cache efficiency.

Q: Can I decode a Base64 string that was copied with extra newlines?

Yes. The tool ignores whitespace inside the input — line breaks, spaces, and tabs are stripped before decoding. PEM-style content (which wraps at 64-76 chars per line) and shell-copied output paste cleanly.

Q: Why does the "likely Base64" indicator say No on valid text?

The detector checks both the character set (only Base64 alphabet allowed, plus padding) and the length (a multiple of 4 for standard Base64). Plain English text usually contains characters outside the Base64 alphabet (spaces, punctuation, etc.) and so is correctly flagged as not-Base64. This is a feature — it prevents the decoder from trying to interpret arbitrary text as Base64 and producing nonsense.

Klartext in Base64 umwandeln und zurück.

Ihre Daten bleiben auf Ihrem GerätKein Upload, kein ServerFunktioniert offline

Mode

Input

Encoded output

aGVsbG8=

Decoded output

—

Input bytes

Looks like Base64

Status

Input looks like plain text; decode skipped.

Warum dieses Tool verwenden

Base64-Werte direkt im Browser enkodieren oder dekodieren – ideal zum Debuggen und Formatieren.

Nützlich beim Arbeiten mit APIs, Tokens und eingebetteten Assets.

Keine Daten verlassen deinen Browser.

So wird's verwendet

01Klartext oder eine Base64-Zeichenkette eingeben.

02Die enkodierte und dekodierte Ausgabe nebeneinander ablesen.

Schnellcheck vor dem Kopieren

Confirm the input is the format you intended.

Scan the result before using it in a document, URL, config, or message.

Copy only the output you need.

FAQ

Werden meine Daten an einen Server gesendet?

Nein. Die gesamte Base64-Kodierung und -Dekodierung erfolgt lokal im Browser.

Ist Base64 eine Form der Verschlüsselung?

Nein. Base64 ist Kodierung, keine Verschlüsselung. Jeder kann Base64-Daten in Sekunden dekodieren. Niemals für sensible Informationen verwenden.

Warum zeigt der dekodierte Text unlesbaren Text?

Wenn die Originaldaten binär waren (Bild, PDF, kompilierte Datei), ist die dekodierte Ausgabe binär und kann nicht als lesbarer Text dargestellt werden.

Was ist der Unterschied zwischen Base64 und Base64url?

Base64url ersetzt + durch -, / durch _ und lässt das =-Auffüllzeichen weg. Es ist URL-sicher und wird in JWTs und einigen API-Tokens verwendet.

Base64 Encoder / Decoder

Klartext in Base64 umwandeln und zurück.

Ihre Daten bleiben auf Ihrem GerätKein Upload, kein ServerFunktioniert offline

Mode

Input

Encoded output

aGVsbG8=

Decoded output

—

Input bytes

Looks like Base64

Status

Input looks like plain text; decode skipped.

Warum dieses Tool verwenden

Base64-Werte direkt im Browser enkodieren oder dekodieren – ideal zum Debuggen und Formatieren.

Nützlich beim Arbeiten mit APIs, Tokens und eingebetteten Assets.

Keine Daten verlassen deinen Browser.

So wird's verwendet

01Klartext oder eine Base64-Zeichenkette eingeben.

02Die enkodierte und dekodierte Ausgabe nebeneinander ablesen.

Schnellcheck vor dem Kopieren

Confirm the input is the format you intended.

Scan the result before using it in a document, URL, config, or message.

Copy only the output you need.

FAQ

Werden meine Daten an einen Server gesendet?

Nein. Die gesamte Base64-Kodierung und -Dekodierung erfolgt lokal im Browser.

Ist Base64 eine Form der Verschlüsselung?

Nein. Base64 ist Kodierung, keine Verschlüsselung. Jeder kann Base64-Daten in Sekunden dekodieren. Niemals für sensible Informationen verwenden.

Warum zeigt der dekodierte Text unlesbaren Text?

Wenn die Originaldaten binär waren (Bild, PDF, kompilierte Datei), ist die dekodierte Ausgabe binär und kann nicht als lesbarer Text dargestellt werden.

Was ist der Unterschied zwischen Base64 und Base64url?

Base64url ersetzt + durch -, / durch _ und lässt das =-Auffüllzeichen weg. Es ist URL-sicher und wird in JWTs und einigen API-Tokens verwendet.

Base64 Encoder / Decoder

Warum dieses Tool verwenden

So wird's verwendet

Schnellcheck vor dem Kopieren

FAQ

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