Arklex vs Promptfoo
Arklex
arklex.ai
Promptfoo
promptfoo.devSide by side
| Figure | Arklex | Promptfoo |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | Yes |
| Web | — | Yes |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 3 |
| Spec score · AI Agent Evaluation Tools | 8.8 (#7) | 8.4 (#11) |
| CI/CD | ArkSim can run in CI pipelines as a quality gate and exits non-zero when quality thresholds are not met. | Promptfoo can run evaluations and security checks in CI/CD pipelines using configuration files and provider credentials. |
| Deployment | Arklex says the platform can run on a customer's infrastructure, and private cloud deployment is available for enterprise customers. | The Community plan can run locally or be self-hosted, while Enterprise includes managed cloud deployment and On-Premise supports deployment on the customer’s infrastructure. |
| Evaluation | Built-in metrics include helpfulness, coherence, relevance, faithfulness, verbosity, goal completion, and agent behavior failure detection; custom metrics are also supported. | It tests prompts across multiple providers, grades outputs with assertions, and calculates accuracy, safety, and performance metrics. |
| Installation | ArkSim can be installed from PyPI with pip or installed from its source repository; its docs require Python 3.10 or later up to 3.13. | Installation is available through npm, npx, Homebrew, and a project dependency; npm and npx require Node.js 22.22.0 or newer. |
| What it does | Arklex evaluates AI agents by generating synthetic user conversations and assessing agent responses across multiple turns. | Promptfoo is a local-first open-source CLI and library for evaluating and red-teaming LLM applications. |
Plans
In their own words
Arklex
Arklex evaluates AI agents with simulated multi-turn conversations, helping teams check how agents respond across scenarios. Its open-source ArkSim framework creates synthetic users with different profiles, goals, and knowledge levels, then assesses responses using built-in measures for helpfulness, coherence, relevance, faithfulness, verbosity, goal completion, and agent behavior failures. Teams can add reusable custom metrics in plain language, review and dispute judge scores, and add human assessments while preserving the original scores. Calibration tracks agreement by metric. Reusable scenarios support comparisons between agent versions and regression checks; ArkSim can also act as a CI quality gate, returning a non-zero result when thresholds are not met. Agents connect through Python classes, Chat Completions HTTP endpoints, or the A2A protocol. The hosted Arklex Platform adds a UI for scenarios, conversations, and scoring. ArkSim is free and open source under Apache-2.0. Its documentation requires Python 3.10 through 3.13 and an API key from OpenAI, Anthropic, or Google; OpenAI is the default provider.
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.