Promptfoo

About Promptfoo

Financials

Dated, source-cited figures. Estimates are marked.

Products by Promptfoo

All products by Promptfoo reviewed by our AI panel of experts.

PromptfooAI Security

LLM evaluation and red teaming for AI applications

From $50/mo8.5/10

How Our Review Panel Scores Promptfoo

Six independent reviewer personalities assessed Promptfoo's product on their own terms. They landed within 0.8 points of each other, an unusually strong consensus.

Averaged across 1 reviewed product in our catalog. Scores are out of 10.

Competitive Landscape

Who Promptfoo competes with, and how they differ.

Braintrust8.0/10

Braintrust is a closed-source enterprise platform for LLM evals and observability (datasets, scoring, CI integration) and is a frequent head-to-head alternative on the evaluation side; unlike Promptfoo it does no adversarial red-teaming or vulnerability scanning.

1 product reviewed on TopReviewed

LangChain8.1/10

LangChain's LangSmith bundles evaluations with tracing and observability and is strongest inside the LangChain framework ecosystem; it targets LLM quality monitoring rather than Promptfoo's security-first red-teaming.

2 products reviewed on TopReviewed

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Lakera

Lakera — acquired by Check Point in 2025 — pairs Lakera Red pre-deployment assessments with Lakera Guard runtime enforcement and sells primarily to security teams, whereas Promptfoo is a developer-first open-source CLI that runs in CI pipelines.

Arize AI8.1/10

Arize pairs its commercial LLM observability platform with the open-source Phoenix evaluation and tracing library; it concentrates on production monitoring and model drift rather than adversarial security testing.

1 product reviewed on TopReviewed

Langfuse8.0/10

Langfuse is an open-source, self-hostable LLM engineering platform (tracing, evals, prompt management) that overlaps with Promptfoo on evaluation workflows but offers no red-teaming or security scanning.

1 product reviewed on TopReviewed

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HiddenLayer6.9/10

HiddenLayer sells an AISec platform — model scanning, automated red teaming, and detection and response — aimed at enterprise security operations securing ML models, rather than Promptfoo's developer evaluation workflow.

1 product reviewed on TopReviewed

Company Timeline

Key milestones in Promptfoo's history, with sources.

1. Mar 9, 2026Acquisition

   Acquired by OpenAI

   OpenAI agreed to acquire Promptfoo to integrate its red-teaming and evaluation technology into OpenAI's model and infrastructure layers. The tool remains open source; at announcement it counted over 350,000 developers, 130,000 monthly active users and adoption at more than 25% of Fortune 500 companies.

   promptfoo.dev
2. Jul 29, 2025Funding

   Series A — $18.4M led by Insight Partners

   Existing investor Andreessen Horowitz participated. By then Promptfoo's open-source tools were used by more than 100,000 developers and adopted at over 30 Fortune 500 companies.

   prnewswire.com
3. Jul 23, 2024Funding

   Seed — $5M led by Andreessen Horowitz

   Angel investors included Shopify CEO Tobi Lutke, Discord CTO Stanislav Vishnevskiy and Okta co-founder Frederic Kerrest. At announcement the open-source evaluation tool was used by over 25,000 engineers at companies including Shopify, Amazon and Anthropic.

   promptfoo.dev
4. 2024Founded

   Promptfoo incorporated by Ian Webster and Michael D'Angelo

   The company was founded in 2024 in San Francisco to help developers systematically test and secure AI applications, building a commercial business on the open-source project.

   promptfoo.dev
5. Apr 28, 2023Launch

   Promptfoo launches as an open-source LLM evaluation tool

   Ian Webster created the promptfoo repository on GitHub under the MIT license. The command-line tool for testing and comparing LLM prompts later expanded into red-teaming and vulnerability scanning for AI applications.

   api.github.com