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StreamData

Free#17 of 27 in Property-Based Testing Tools

StreamData: A focused, open-source choice for repeatable property-based testing in ExUnit. Ranked #17 of 27 in Property-Based Testing Tools by our editors (7.7/10); pricing: Free plan; best for elixir teams using ExUnit.

7.7/10★★★★☆Editor score

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At a glance

• Editor score
  7.7 / 10
• Pricing
  Free plan
• Best for
  Elixir teams using ExUnit
• Free plan
  Yes
• Paid from
  Free
• Supported languages
  Elixir
• Facts checked
  20 Sep 2026

• Where it wins

  • Composable generators cover common Elixir data types and custom construction.
  • Shrinking reduces failures to smaller counterexamples.
  • Seeded generation supports deterministic reproduction of failures.

• Where it doesn't

  • Supports Elixir rather than multiple programming languages.
  • Designed for ExUnit rather than a broad range of test runners.
  • Does not provide verified stateful testing.

Our verdict on StreamData

StreamData is an open-source Elixir library for generating test data and writing property-based tests. It is aimed at Elixir developers working on applications and libraries who need randomized, repeatable testing. Its ExUnitProperties integration connects property checks with ExUnit, while composable generators cover common Elixir data types and support custom generator construction. Infinite randomized generator streams, filtering, and binding give teams control over how test values are produced.

The library’s pricing model is straightforward: StreamData is free and open source, with no paid tiers described. Its strongest technical depth is in generator-driven testing. Generated values can be shrunk to smaller counterexamples when a property fails, and seeded generation supports deterministic reproduction. Together, these features make it suitable for investigating failures without giving up randomized input generation. The generator model also supports reusable building blocks for application- or library-specific data.

StreamData fits most directly into an Elixir and ExUnit ecosystem. That focused integration is useful for teams already working in that stack, but it narrows the audience for projects using other languages or test runners. It also does not provide verified stateful testing, so teams testing complex state transitions should consider a tool with that capability. Choose StreamData for composable data generation, property checks, shrinking, filtering, binding, and reproducible failures in ExUnit; look elsewhere when cross-language coverage or stateful testing is central.

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StreamData pricing

StreamData fact sheet

Alternatives to StreamData

• fast-checkA deep, runner-agnostic testing library for JavaScript and TypeScript teams.9.4
• HypothesisA focused Python library for generated inputs, shrinking, and stateful tests.9.3
• ProptestA focused Rust framework for generated inputs, shrinking, replay, and stateful tests.9.1

See all StreamData alternatives →

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Featured on iTechGuides

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 7 Oct 2026 · How we research and update