LangTest

Open-source behavioral testing for language models and NLP systems

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PricingFree
Starting price$0
Free planYes
Free trialNo
APIYes
Open sourceYes
DeploymentSelf Hosted
Last verifiedAugust 2, 2026
Overview

Tool overview

LangTest is listed under AI Governance Safety & Evaluation AI tools.

Summary

What is LangTest?

LangTest is an Apache-2.0 Python library for testing language models and NLP systems across robustness, bias, fairness, representation, accuracy, safety, and domain benchmarks.

Best fit

Best for

Teams building reproducible language-model quality tests

Audience

Who is it for?

ML engineersResponsible-AI teamsNLP researchersHealthcare AI teams
Recommendation

Decision note

Rebuilt from the original export under the complete V412/V411 factual-source-verification workflow. Preview only. Apply remains blocked until Failures = 0, Warnings = 0, Unmapped = 0, Missing = 0; explicit clears are reviewed; image import is disabled; a representative WordPress edit screen is compared with the export and proposed row; and a post-Apply zero-change Preview succeeds.

Capabilities

Key features

More than 60 automated test types

Robustness, bias, fairness, safety, and accuracy testing

LLM, NLP, legal, and clinical benchmarks

Harness API, reports, and data augmentation

Workflows

Use cases

Evaluate LLM and NLP behavior

Create regression gates for releases

Test healthcare and legal models

Generate robustness and bias test cases

Strengths

Pros

  • Free and Apache-2.0 licensed
  • Supports many model providers and NLP frameworks
  • Works in notebooks and CI pipelines
Considerations

Limitations

Automated tests do not replace domain-expert review.

Benchmark coverage and language support depend on the selected model, task, and dataset.

Cost

Pricing details

Pricing modelFree
Starting price$0
Free planYes
Free trialNo
Pricing context

Billing options

Free open-source softwareModel-provider usage
Pricing context

Pricing note

LangTest is free under Apache-2.0. External model APIs and compute are billed separately by their providers.

View official pricing
Compatibility

Supported languages

  • Multiple languages through supported models and datasets
Connectivity

Integrations

Hugging Face

OpenAI

Cohere

AI21

Azure OpenAI

spaCy

John Snow Labs

Specs

Technical details

PlatformsWeb
Multilingual supportYes
Login requiredNo
Open sourceYes
LicenseApache-2.0
DeploymentSelf Hosted
CompanyPacific AI / John Snow Labs
Current version2.7.0
Editions / plansLangTest open-source library Pacific AI enterprise governance services
Data confidenceHigh
Last verifiedAugust 2, 2026
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Answers

Frequently asked questions

LangTest is an Apache-2.0 Python library for testing language models and NLP systems across robustness, bias, fairness, representation, accuracy, safety, and domain benchmarks.
Teams building reproducible language-model quality tests
The listed pricing model for LangTest is free. Pricing can change, so users should verify the latest plan details on the official website.
The current profile does not indicate an available free trial. Check the official website before purchasing.
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