Beauty & Personal Care

Backtest a forecasting method on the input series by holding out the last `testSize` ob…

Forecast backtest (MAPE + RMSE)

Backtest a forecasting method on the input series by holding out the last `testSize` observations, forecasting them, and computing MAPE (mean absolute percentage error)…

Holt's linear trend method - level + trend (no seasonality)

Forecast (Holt linear trend)

Holt's linear trend method - level + trend (no seasonality). Two smoothing parameters: alpha (level) and beta (trend). Forecast extrapolates as a straight line from the…

Decompress a base64-encoded gzip payload

Gzip decompress

Decompress a base64-encoded gzip payload. Returns the result as utf8 (text) or base64 (binary). Refuses to expand past 10MB to defend against zip bombs.

Three textbook baseline forecasts: mean (forecast = average of history), naive (forecas…

Forecast (naive baselines)

Three textbook baseline forecasts: mean (forecast = average of history), naive (forecast = last value), drift (linear extrapolation from first to last point). Use as a s…

Simple exponential smoothing (SES) - level-only forecast for series without trend or se…

Forecast (simple exponential

Simple exponential smoothing (SES) - level-only forecast for series without trend or seasonality. Higher alpha (closer to 1) tracks recent values aggressively; lower alp…

Great-circle distance between two latitude/longitude points using the haversine formula

Geo distance (haversine)

Great-circle distance between two latitude/longitude points using the haversine formula. Returns kilometers and miles. Deterministic.

Hex encode or decode text

Hex

Hex encode or decode text. mode: encode (default) or decode.

HMAC signature of a message with a shared key

HMAC

HMAC signature of a message with a shared key. Algorithms: sha256 (default), sha512, sha1. Returns hex and base64.

Encode text to HTML entities or decode them back

HTML entities

Encode text to HTML entities or decode them back. mode: encode (default) or decode.

Extract <title>, <meta description>, OpenGraph/Twitter cards, canonical URL, and JSON-L…

HTML meta (from string)

Extract <title>, <meta description>, OpenGraph/Twitter cards, canonical URL, and JSON-LD blocks from an HTML string. Distinct from /api/meta which fetches a URL - feed t…

Enumerate every <a href> in an HTML string with its anchor text and rel attribute

HTML links

Enumerate every <a href> in an HTML string with its anchor text and rel attribute. Optionally resolves relative hrefs against a base URL and filters by a regex on the hr…

Convert an HTML fragment or document you already have into clean markdown

HTML to Markdown

Convert an HTML fragment or document you already have into clean markdown. (To fetch + convert a live URL, use /api/extract.)

Validate an IBAN: country code, length, and the ISO 13616 mod-97 checksum

IBAN validate

Validate an IBAN: country code, length, and the ISO 13616 mod-97 checksum.

Compute the internal rate of return (IRR) of a cashflow stream - the discount rate at w…

Internal rate of return (IRR)

Compute the internal rate of return (IRR) of a cashflow stream - the discount rate at which NPV = 0. Index 0 is treated as t=0 (typically the negative initial investment…

Deep-compare two JSON values

JSON diff

Deep-compare two JSON values. Returns a list of changed/added/removed paths (capped at 1000 differences).

Get the ISO 8601 week number, ISO day-of-week, quarter, and day-of-year for any date

ISO week number

Get the ISO 8601 week number, ISO day-of-week, quarter, and day-of-year for any date. Useful for fiscal/reporting calendars, weekly aggregations, and sprint planning.

Flatten nested JSON to dot-path keys, or unflatten dot-path keys back to nested JSON

JSON flatten/unflatten

Flatten nested JSON to dot-path keys, or unflatten dot-path keys back to nested JSON. mode: flatten (default) | unflatten.

Validate, pretty-print (any indentation, 0-8 spaces), or minify JSON, optionally with o…

JSON validate & format

Validate, pretty-print (any indentation, 0-8 spaces), or minify JSON, optionally with object keys sorted. canonical: true returns the RFC 8785 (JCS) canonical form - key…

Resolve an RFC 6901 JSON Pointer (e.g

JSON pointer

Resolve an RFC 6901 JSON Pointer (e.g. /items/0/name) against a JSON value. Returns the value or found:false.

Extract a value from JSON by dot/bracket path, e.g

JSON query

Extract a value from JSON by dot/bracket path, e.g. "items[2].name".

Convert between a JSON array and JSONL/NDJSON (one JSON object per line)

JSONL convert

Convert between a JSON array and JSONL/NDJSON (one JSON object per line). mode: to-jsonl (array → lines) or from-jsonl (lines → array). For streaming records to and from…

Verify an HS256/384/512 JWT signature against a secret and check expiry

JWT verify (HMAC)

Verify an HS256/384/512 JWT signature against a secret and check expiry. Returns valid + decoded payload. (HMAC algorithms only.)

Check whether a year is a leap year and get related info: days in that year, the next a…

Leap year check

Check whether a year is a leap year and get related info: days in that year, the next and previous leap years, and the Gregorian leap-year rule.

Levenshtein edit distance between two strings, plus a 0-1 similarity ratio

Edit distance

Levenshtein edit distance between two strings, plus a 0-1 similarity ratio.