Base36 encoder

You supply a value and a direction: to_base36 maps a whole number into uppercase base-36 digits, and from_base36 maps a case-insensitive base-36 string into a decimal integer. The engine is fully deterministic: encode peels remainders of thirty-six from the magnitude; decode accumulates digits with a left-to-right Horner scheme; invalid base-36 characters fail with a clear invalid_input error.

What base-36 conversion means and what the response contains

This calculator returns the original value echo, a normalized direction tag of to_base36 or from_base36, the decimal integer and its decimal_string form, an uppercase base36 string plus a base36_lower convenience field, a method tag base36, a short formula reminder of both remainder and Horner steps, and the base_from and base_to numbers for documentation. The engine either builds an exact conversion for a whole number or valid base-36 string inside the supported magnitude or rejects the input with invalid_input. Rejected cases include a missing value or direction, an empty string after trimming, a bare sign with no digits, non-integer decimal input when encoding, any invalid base-36 character when decoding, Infinity or NaN, and any magnitude larger than the documented maximum so results stay inside Number.MAX_SAFE_INTEGER.

How value and direction are read and how results stay reproducible

Outer whitespace is trimmed. When encoding, an optional leading plus or minus is allowed, then the remaining characters must be decimal digits only—no spaces, commas, underscores, decimal points, or exponent markers. A bare JavaScript number is accepted only when it is a finite integer. Encode uses repeated remainder extraction on the absolute value with uppercase output digits; decode uses Horner accumulation and normalizes the base36 field to uppercase. Zero maps to the single digit zero in both directions. The preferred field for the payload is value, but aliases v, input, text, number, n, decimal, and base36 are accepted so query strings, spreadsheets, and typed forms can reuse the same contract without renaming columns. Direction is required and selects the mapping: to_base36, to, encode, or decimal_to_base36 means treat value as a whole number and emit base-36 digits; from_base36, from, decode, or base36_to_decimal means treat value as a base-36 string and emit a decimal integer. When decoding, digits may be uppercase or lowercase A through Z, and an optional leading sign is allowed; any other character, including underscores, spaces, and punctuation, fails with invalid_input and a message that names the invalid base-36 character so a bad cell does not become a wrong integer. Magnitude is capped at Number.MAX_SAFE_INTEGER so JSON goldens compare without BigInt serialization quirks and every result is a safe integer path. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing base-36 conversion yourself.

Where base-36 conversion fits in study, product codes, and software

On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split—free interactive exploration and a priced, identical API—matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result.