# wolfcw/libfaketime

libfaketime modifies the system time for a single application

Repository: https://github.com/wolfcw/libfaketime
Canonical: https://ross.abutalabs.com/products/libfaketime
Homepage: https://github.com/wolfcw/libfaketime
Language: C
License: GPL-2.0
License Family: copyleft
Topics: ld-preload, datetime, wrapper, intercept-calls, reproducible-builds, hacktoberfest
Last push: 2026-08-19T07:58:50+00:00

## Health v2 (maintenance only)
Score: 78/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 40, longevity 100
- inputs: {"age_days": 5610, "days_push": 14, "days_rel": 450, "gap_med": 15, "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 3106, forks 377 (observed 2026-08-28T04:07:43.773070+00:00)

## What it is
libfaketime is an LD_PRELOAD library that intercepts system calls retrieving the current date and time, reporting faked times to a single application without changing the system clock. It ships with a 'faketime' command-line wrapper and supports absolute dates, relative offsets, and deterministic time sequences.

## Use cases
- fake the system time for a single program
- make builds reproducible with fixed timestamps
- debug expired SSL certificate issues
- test software for year-2038 compliance
- run an application with a date in the past or future
- mock time in tests without changing the system clock

## When to choose
- you need to control the time a single process sees without root or system-wide changes
- you want reproducible builds with deterministic timestamps
- you are debugging time-dependent behavior like certificate expiry

## When to avoid
- the target binary is statically linked or setuid, since LD_PRELOAD cannot intercept it
- you need to fake time on Windows or non-UNIX platforms
- you need monotonic clock faking for JVM apps without extra configuration

## Facets
- artifact type: library
- maturity: active
- function: date-time, testing, developer-tools
- domain: developer-tools, testing
- platform: cli, cpp, c
- tags: ld-preload, time-mocking, reproducible-builds, system-call-interception, faketime, command-line, linux, macos

## Member repositories
- wolfcw/libfaketime (main) score 78

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:43.773070+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 2026-08-29T18:46:10.305524+00:00, confidence not recorded.
  - readme: https://github.com/wolfcw/libfaketime (fetched 2026-08-28T04:07:43.773070+00:00, sha bd8336b8c6e0)
  - homepage: https://github.com/wolfcw/libfaketime (fetched 2026-08-29T09:41:58.469967+00:00, sha 2aa0d8eea28c)
- Data as of 2026-08-30T08:39:29.467469+00:00.