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Open-source test data and mocking tools: 23 compared

Fake data generators, mock servers and service virtualisation.

23 tools are listed here, 1 of them with this as a secondary category. Each one is open source under an OSI-approved license and meets the inclusion rules. The table is sorted by GitHub stars, descending, on the fetch date. Select a column heading to sort by another column.

Metrics as of , from the GitHub or GitLab API of each repository. Refreshed monthly.

Test data and mocking tools. Sorted by GitHub stars, descending. Select a column heading to change the sort.
JSON Server75,71512026-03-231v1.0.0-beta.152026-03-231MITJavaScriptslow
Faker19,40512026-09-141v40.39.02026-09-151MITPythonactive
Mock Service Worker18,21612026-07-081v2.15.02026-09-081MITTypeScriptactive
@faker-js/faker15,49312026-08-141v10.6.02026-09-221MITTypeScriptactive
Mockito15,45712026-03-111v5.23.02026-09-091MITJavaactive
Nock13,12612026-07-301v14.0.172026-07-301MITJavaScriptactive
Sinon.JS9,75912018-01-261v4.2.22026-07-201BSD-3-ClauseJavaScriptactive
Bogus9,73612025-10-261v35.6.52025-12-221MITC#slow
Karate8,96512026-08-141v2.1.22026-09-191MITJavaactive
Testcontainers for Java8,74112026-04-2012.0.52026-09-091MITJavaactive
Mockoon8,41712026-09-161v9.9.02026-09-201MITTypeScriptactive
factory_bot8,16912026-05-041v6.6.02026-08-211MITRubyactive
WireMock7,37812025-11-1413.13.22026-09-221Apache-2.0Javaactive
Prism5,03412026-07-171v5.16.02026-09-211Apache-2.0TypeScriptactive
Testcontainers for Go4,98812026-08-071v0.44.02026-09-211MITGoactive
MockServer4,97412026-09-151mockserver-8.0.02026-09-221Apache-2.0Javaactive
Responses4,34212026-08-2610.26.32026-09-161Apache-2.0Pythonactive
Testcontainers for Node.js2,61312026-08-041v12.1.02026-09-211MITTypeScriptactive
Hoverfly2,52212026-09-211v1.12.152026-09-211Apache-2.0Goactive
Testcontainers Python2,30112026-07-241testcontainers-v4.15.02026-09-141Apache-2.0Pythonactive
mountebank2,10512026-04-151v2.9.42026-09-121MITJavaScriptactive
Microcks2,04612026-08-0511.15.02026-09-221Apache-2.0Javaactive
Datafaker1,79712026-06-2412.7.02026-09-211Apache-2.0Javaactive

1 Fetched from the GitHub or GitLab API on . Hover a value for its own date.

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Open-source test data tools: how the list is sorted and what each covers