Base62 Decode

100% client-side processing (no server upload). Decode Base62 back into its original text (byte-accurate via charset), with selectable alphabets, optional data:*;base62, prefix handling, and strict validation for debugging.

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About Base62 Decode (Text)

Paste Base62 input, pick the correct alphabet and charset, then click "Decode" to recover the original text. Output is deterministic for the same options, and strict validation can surface corruption or alphabet mismatches. Need the opposite direction? Use the other page.

Features

Decode Base62 to text (byte-accurate via selected character set)
Alphabet selection for compatibility (0-9A-Za-z, 0-9a-zA-Z, A-Za-z0-9, a-zA-Z0-9)
Accept data:*;base62, prefix (optional) to decode copied data URIs
Process line by line for lists of Base62 values
Strict validation to reject invalid characters (and invalid length where applicable)
Live preview for small inputs while you type
100% client-side processing (no server upload).

How to use for base62-decoder

Paste or drop content

Paste your Base62 string into the input editor (you can also drop text files such as .txt, .json, .md). If your input includes a data:*;base62, prefix, keep it as-is and enable prefix stripping.

Click "Decode"

Choose the matching "Alphabet" and "Character set" (default UTF-8), then click "Decode". Optionally enable "Strict validation" to fail fast on malformed input.

Copy or download

Copy the decoded text from the output editor, or download the result as a text file for later use.

Technical specifications

Execution Model

Runtime disclosure and operational constraints.

Aspect	Detail
Runtime	100% client-side processing (no server upload).
Action scope	Decoding only (this page)
Input type	Text (Base62 string); optional data:*;base62, prefix stripping
Output type	Text (decoded bytes interpreted via selected charset)
Limits	~1–2MB chars; ~25000 ms timeout
Retention	All processing happens locally in your browser (no upload)

Avoid pasting secrets into online tools. Even with local processing, sensitive data can leak via browser extensions, screen sharing, or shared devices.

Mini Example

A minimal decode round-trip illustration using the tool's built-in example pair.

Field	Value
Input (Base62)	T8dgcjRGuYUueWht
Output (text)	Hello World

If your result looks garbled, the most common causes are a wrong "Alphabet" selection or a mismatched "Character set".

Errors & Edge Cases

Common failure modes and how to resolve them.

Symptom	Likely cause	What to check
Invalid characters / strict validation fails	Input contains characters not present in the chosen Base62 alphabet	Select the correct "Alphabet"; ensure the string wasn't modified (copy/paste, wrapping)
Decoded text is unreadable (mojibake)	Wrong character set used to interpret decoded bytes	Try the correct "Character set" (UTF-8 is default; other charsets may be needed for legacy data)
Input too large (max 2MB)	The tool enforces a ~2MB character limit	Split the input, decode in parts, or switch to a local script for large payloads
Adapter call timed out	Decoding exceeded the ~25000 ms timeout	Reduce input size, disable live preview, and decode on demand
Decoding a list fails mid-way	One of the lines is malformed when processing line by line	Enable "Strict validation" to find the first failing line; verify separators/newlines
data:*;base62, prefix breaks decoding	Prefix wasn't stripped or the data URI is malformed	Enable "Accept data:*;base62, prefix" and ensure the header ends before the payload

Command line alternatives

For sensitive data, automation, or CI, prefer local execution. Base62 typically requires choosing an explicit alphabet (there is no universal built-in Base62 CLI across platforms).

Node.js (all platforms)

Decode Base62 with an explicit alphabet (library-based)

node -e "const baseX=require('base-x'); const alphabet='0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'; const b62=baseX(alphabet); const s=process.stdin.read().trim(); const buf=b62.decode(s); process.stdout.write(buf.toString('utf8'));" < input.b62

Match the alphabet to your tool's "Alphabet" setting. Convert bytes to text using the appropriate charset (utf8 shown here).

Python (all platforms)

Decode Base62 to bytes locally (library-based)

python -c "import sys; import base62; s=sys.stdin.read().strip(); sys.stdout.write(base62.decodebytes(s).decode('utf-8', errors='strict'))" < input.b62

Decode to bytes, then decode bytes to text using the right charset. Swap 'utf-8' if your data is legacy-encoded.

Use cases

Recover text payloads from Base62 tokens

Decode Base62 identifiers back to their original strings
Inspect payloads embedded in Base62 for debugging

Debug alphabet mismatches between systems

Confirm whether a partner system uses 0-9A-Za-z vs A-Za-z0-9
Standardize and document the Base62 alphabet across teams

CI checks for corrupted Base62 inputs

Enable strict validation to fail fast on invalid characters
Detect truncation or accidental character substitution in stored tokens

Safer local inspection of untrusted inputs

Decode suspicious strings locally in-browser without uploading content
Avoid sharing raw decoded outputs in logs when not necessary

❓ Frequently Asked Questions

Is there a public API?

No. This page is designed for interactive use and does not expose a public API endpoint.

Is processing local or remote?

Processing is local: 100% client-side processing (no server upload). All processing happens locally in your browser (no upload).

Can I decode secrets safely here?

Avoid decoding secrets in a browser on shared machines. Even with local processing, sensitive data can leak via extensions, clipboard history, screen recording, or accidental sharing. Prefer offline tooling for secrets.

Why does decoding fail with an invalid character or validation error?

Most failures come from using the wrong "Alphabet" (Base62 isn't universally standardized), copying a truncated string, or introducing characters during formatting (spaces/newlines). Select the correct alphabet variant, keep the payload intact, and enable "Strict validation" to surface the first incompatibility.

Pro Tips

Best Practice

If decoding output looks wrong, change "Alphabet" first—Base62 alphabets are not standardized and mismatches are extremely common.

CI Tip

Use "Strict validation" when debugging or validating stored tokens to catch corruption early.

Performance Tip

Disable "Live preview" for bigger inputs to avoid repeated work and reduce the risk of timeouts (~25000 ms).