Chance.js

At a glance

• Editor score
  6.5 / 10
• Pricing
  Free plan
• Best for
  Lightweight JavaScript random values
• Free plan
  Yes
• Paid from
  Free
• Generation modes
  Synthetic
• Founded
  2013
• Facts checked
  20 Sep 2026

• Where it wins

  • Seeded generation supports repeatable random sequences.
  • Configurable strings, addresses, dates, and GUIDs.
  • Runs in browsers and Node.js with MIT licensing.

• Where it doesn't

  • Developer library rather than a hosted test-data platform.
  • No relational dataset workflow or database connectors.
  • Narrower coverage than libraries with file-generation features.

Our verdict on Chance.js

Chance.js is an open-source JavaScript library for generating pseudo-random values in automated tests and other development tasks. It suits developers who need synthetic data directly in browser code or Node.js applications, rather than teams looking for a hosted workspace. The documented generators cover strings, numbers, names, addresses, dates, GUIDs, web values, locations, and finance-related values. Its MIT License and free open-source model make it a practical fit for lightweight test-data generation within JavaScript projects.

The library’s strongest feature is control over repeatable output. Seeded generation can produce the same random sequence across runs, which is useful when test cases need consistent inputs. String generation supports configurable length, character pools, casing, and symbols. Date values can be returned as date objects or strings, while GUID generation supports selectable versions. Browser use is available through a script include, and Node.js projects can install and use it as a module. These options keep common synthetic-data tasks close to the application code.

Chance.js is more focused than a full test-data platform or a broader developer library. It does not provide a hosted interface, database connectors, or a relational dataset workflow, and its verified feature breadth does not include file-generation coverage. Choose it when JavaScript-native random values, repeatable sequences, and straightforward integration are the priority. Teams that need connected datasets, generated files, or broader workflow coverage should consider a tool designed around those requirements instead.

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Chance.js pricing

Chance.js fact sheet

Alternatives to Chance.js

• MOSTLY AIA broad synthetic-data platform for enterprise relational data teams.9.4
• SynthesizedA database-focused platform for schema-faithful synthetic data and protected test environments.9.2
• Tonic FabricateA flexible choice for AI-assisted relational test data with API and export workflows.9.0

See all Chance.js alternatives →

Featured on iTechGuides

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 7 Oct 2026 · How we research and update