# supabase-community/copycat

Generate deterministic fake values: The same input will always generate the same fake-output.

Repository: https://github.com/supabase-community/copycat
Canonical: https://ross.abutalabs.com/products/copycat
Homepage: https://www.snaplet.dev
Language: TypeScript
License: MIT
License Family: permissive
Topics: deterministic, fake, fake-data, fake-data-generator, database-seeding
Last push: 2025-01-14T21:24:37+00:00

## Health v2 (maintenance only)
Score: 26/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 1, release rhythm 16, longevity 100
- inputs: {"age_days": 1590, "days_push": 596, "days_rel": 596, "gap_med": 96, "n_releases_24m": 2}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1057, forks 38 (observed 2026-08-28T04:03:24.912876+00:00)

## What it is
Copycat is a TypeScript library for generating deterministic fake values, where the same input always maps to the same fake output. It uses SipHash under the hood so replacements are stateless and cannot easily be reversed to infer the original input.

## Use cases
- generate deterministic fake data for database seeding
- anonymize sensitive data by replacing values with consistent fakes
- create stable test fixtures that don't change between runs
- replace faker when I need input-to-output determinism
- seed demo environments with reproducible fake emails and names

## When to choose
- you need the same input to always produce the same fake value regardless of call order or environment
- you are anonymizing or masking production data while preserving referential consistency
- you want stateless fake data generation without managing PRNG seeds

## When to avoid
- you need realistic locale-specific or highly varied fake data rather than deterministic mappings
- you just need a random sequence of fake values and don't care about determinism
- you need fake data in a language other than JavaScript/TypeScript

## Facets
- artifact type: library
- maturity: active
- function: data-generation, serialization
- domain: developer-tools, testing, privacy
- platform: cross-platform
- tags: fake-data, deterministic, database-seeding, data-anonymization, test-data, data-engineering, nodejs, typescript

## Member repositories
- supabase-community/copycat (main) score 26

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:24.912876+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:58:00.410677+00:00, confidence not recorded.
  - readme: https://github.com/supabase-community/copycat (fetched 2026-08-28T04:03:24.912876+00:00, sha ffc2d903f240)
- Data as of 2026-08-30T08:39:29.467469+00:00.