Generate an RFC 6238 time-based one-time password from a base32 secret. Uses the current time by default, or an explicit unix timestamp (seconds); configurable period (default 30s), digits (default 6) and algorithm (default SHA1). Also returns the counter and seconds remaining in the window.

Count the LLM tokens in text for a given model or encoding — exact for OpenAI and open models (Llama, Mistral, Qwen, Gemma, DeepSeek, Command-R); labelled-approximate for Claude & Gemini.

CRC-16 over the input payload in one of several standard variants (ccitt-false, xmodem, modbus, ibm; default ccitt-false). Returns the checksum as an unsigned integer and 4-digit hex. Non-cryptographic.

CRC-32 (IEEE 802.3 polynomial, as used by zip, gzip and PNG) over the input payload. Returns the checksum as an unsigned integer and 8-digit hex. Non-cryptographic — for error detection only.

Add, subtract, multiply or divide two fractions and return the exact, fully-reduced result. All computation is done in BigInt so there is no floating-point error. Dividing by a zero fraction is a clean 400.

Return the synonyms of an English word, aggregated across all its senses. Optionally filter by part of speech. An unknown word returns found:false with a 200.

Multifamily development underwriting — construction to hold to exit. Models construction draws (S-curve or straight-line), capitalized interest, lease-up ramp, construction-to-perm refi, and hold period returns. Returns development yield on cost, spread to cap rate, profit on cost, IRR and MOIC.

Single-Family Rental (SFR) underwriting — monthly buy-and-hold proforma to unlevered AND levered project returns (IRR via XIRR + equity multiple). Loan-to-cost financing, optional interest-only, appreciation-floored exit. Deterministic, Excel-reconciled, SHA-pinned (pass attest=true).

Multifamily acquisition underwriting — mixed unit mix through a monthly proforma to unlevered AND levered project returns (IRR via XIRR + equity multiple). Stub acquisition month, trailing-NOI exit. Deterministic, Excel-reconciled, SHA-pinned (pass attest=true).

Expand a fraction to its decimal form by exact long division, detecting a repeating cycle and rendering it in parenthesis notation (e.g. 1/6 → '0.1(6)', 1/7 → '0.(142857)'). maxDigits caps a non-repeating expansion. A zero denominator is a clean 400.

Deep structured analysis of one project by slug: what it is, entry, signature needs, risks, verdict.

Euler's totient φ(n) — the count of integers in [1, n] coprime to n — for a positive integer ≤ 10^15 (it is computed from the prime factorization).

Generate an RFC 4226 counter-based HMAC one-time password from a base32 secret and counter. Configurable digits (6–10, default 6) and algorithm (SHA1/SHA256/SHA512, default SHA1). An invalid base32 secret is a clean 400.

Evaluate one or more percentiles (0–100) of a numeric sample using linear interpolation between order statistics (the R-7 / Excel PERCENTILE.INC method). 50 is the median, 25/75 the quartiles.

Verify a submitted TOTP code against a base32 secret, scanning ±window time steps (default ±1) to tolerate clock drift. Returns valid plus the matching step offset (delta). A code that does not match is a successful result with valid=false — not an error.

Compute a keyed HMAC of some data with a secret key — the standard way to sign and verify webhooks (Stripe, GitHub, etc.) and API requests. Data and key may each be utf8/hex/base64/base64url; the tag is returned as hex/base64/base64url.

Jaro similarity and the Jaro-Winkler variant (which boosts scores for a shared prefix), both in [0,1]. The prefix boost factor is configurable (default 0.1, max 0.25). Well suited to short strings like names.

Compute a cryptographic digest (SHA-2, SHA-3, BLAKE2, and legacy SHA-1/MD5/RIPEMD-160) of some data. The input may be utf8/hex/base64/base64url and the digest is returned as hex/base64/base64url.

Compute (base ^ exponent) mod modulus efficiently for arbitrary-precision integers. The modulus must be positive.

Search the constants table by key, symbol or name substring. Exact matches rank first, then prefix matches, then substring matches. Returns up to `limit` constants (default 20) plus the total match count.