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HELM vs Promptfoo

HELM

crfm.stanford.edu

Promptfoo

promptfoo.dev

Side by side

FigureHELMPromptfoo
Price fromFreeFree
Free planYesYes
Free trial——
Open source—Yes
WebYesYes
Windows—Yes
macOS—Yes
Linux—Yes
APIYesYes
Self-hostedYesYes
Plans published13
Spec score · LLM Evaluation Tools8.3 (#7)8.4 (#6)
Spec score · AI LLM Evaluation Tools8.4 (#12)8.4 (#13)
Founded20222024
InstallationThe project instructs users to install HELM from PyPI with `pip install crfm-helm`.Installation is available through npm, npx, Homebrew, and a project dependency; npm and npx require Node.js 22.22.0 or newer.
LicenseThe repository identifies HELM as open source and links to an Apache-2.0 license.The open-source project is distributed under the MIT license.
Model providersModels from providers including OpenAI, Anthropic, and Google are accessible through a unified interface.Provider documentation covers OpenAI, Anthropic, Google, Vertex, HTTP, JavaScript, Python, Ruby, shell, OpenAI Agents, and other services.
SupportUsers are directed to open GitHub issues for questions, which maintainers address when bandwidth is available.Community support is provided through chat and GitHub issues, while Enterprise includes professional services and dedicated Slack support.

Plans

HELM

  • HELMFree

HELM pricing →

Promptfoo

  • CommunityFree
  • EnterprisePriced on request
  • On-PremisePriced on request

Promptfoo pricing →

In their own words

HELM

HELM is an open-source Python framework for evaluating foundation models, including large language and multimodal systems. It supplies standardized datasets and benchmarks such as MMLU-Pro, GPQA, IFEval, and WildBench, with a unified interface for models from providers including OpenAI, Anthropic, and Google. Evaluations can examine accuracy, efficiency, bias, and toxicity, and can include custom metrics, LLM-as-a-judge checks, safety evaluations, and human review workflows. Users can configure private checkpoints or model servers, run inference locally, or send requests to an API. A web interface displays individual prompts and responses, while leaderboards compare models and benchmarks across areas such as medicine, finance, multilinguality, and world knowledge. HELM can reproduce published evaluation results and documents commands for running benchmarks, summarizing results, and starting a local server. It is free, Apache-2.0 licensed, and entered maintenance mode on June 1, 2026.

Visit crfm.stanford.edu

Promptfoo

Promptfoo helps developers and enterprises evaluate prompts and test AI applications for security risks. It compares prompt outputs across multiple models in a web view. Red-team testing simulates users to look for prompt injections, jailbreaks, data leaks, business rule violations and insecure agent tool use. Its getting-started guide lists more than 60 providers, including OpenAI, Anthropic, Google and local models such as Ollama. Integrations include CI systems such as GitHub Actions, GitLab CI, Jenkins, Azure Pipelines, CircleCI and Bitbucket Pipelines, plus Splunk, Burp Suite, Google Sheets and MCP. Installation is available through npm, npx or Homebrew. Promptfoo requires Node.js 22.22.0 or newer and recommends Node.js 24 LTS. The free Community plan includes all LLM evaluation features and 10k red-team probes per month, and can run locally or be self-hosted. Enterprise includes managed cloud deployment; On-Premise runs on customer infrastructure. Promptfoo says it is based in San Francisco, is now part of OpenAI and remains open source.

Visit promptfoo.dev