Strictly decode standard or URL-safe Base64 into UTF-8 text, with explicit malformed-input errors and an untrusted-output security boundary.
A quick decision brief for this specific tool
Base64 Input
Decoded
A dedicated interactive panel for this data format or operation
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Decode one standard or URL-safe RFC 4648 Base64 text into canonical UTF-8 while rejecting malformed alphabet, padding, length and byte sequences and treating every decoded character as untrusted text.
Decode padded or unpadded standard/URL-safe Base64 without an auto-detect mode silently reversing the task.
Paste an authorized fixture, inspect strict errors and exact UTF-8 output, then save the three-field Project record.
The decoded text matches the producer bytes and the chosen Tool does not encode instead.
Prevent decoded markup, script, credentials or binary bytes from being treated as safe or authenticated.
Use a redacted non-secret fixture, retain the visible trust boundary and review output only as inert text.
No decoding result is executed, navigated, rendered as markup or accepted as origin/integrity evidence.
Verify CJK, accents and emoji while receiving explicit errors for non-UTF-8 bytes and malformed Base64.
Exercise both alphabets, padding and whitespace cases with labeled input/output/copy/save controls.
Can reproduce valid text and understand every rejection without relying on color.
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
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Whitespace is removed, alphabet and padding positions are checked, standard and URL-safe symbols are normalized, and impossible modulo-four lengths are rejected.
Decoded bytes pass through a fatal UTF-8 decoder. Re-encoding must reproduce the canonical unpadded input, preventing silent replacement or ambiguous text output.
The result is placed in a read-only text control. It is not navigated, executed, rendered as HTML, authenticated, decrypted, or approved for another system.
Updated: August 2026
A developer decodes an authorized URL-safe, unpadded fixture and saves the exact input, UTF-8 output, and untrusted-data warning to the security review.
A reviewer confirms that invalid alphabet, padding, length, noncanonical text, and non-UTF-8 bytes fail rather than producing replacement characters.
A security reviewer decodes a synthetic markup-like value but keeps it inert and refuses to treat Base64 or the displayed result as trustworthy.
Decode one authorized Base64 fixture as strict UTF-8 text. The focused route accepts both RFC 4648 alphabets and optional padding, but never treats decoded content as safe, authenticated, or secret.
