Stop eyeballing your prompts.
Start testing them.

PromptLens is a prompt testing and evaluation platform for teams building LLM-powered applications. Create test cases, run evaluations, and share results with your team. No YAML. No CLI. Just paste and test.

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Evaluation Results
v12 → v13Regression detected

Before

84%

After

71%

−13%
50 test cases8 failed

"How do I reset my password?"

Missing password reset link in response

Test prompts across all major models

OpenAI
Anthropic
Google
Meta
DeepSeek
Mistral
The Problem

Every team ships broken prompts.
Most don't know until users complain.

You tweak a prompt, eyeball the output, and push to production. Two weeks later, edge cases surface. By then, your users already noticed.

Without PromptLens

  • Manual testing in ChatGPT playground
  • "Looks good to me" as QA process
  • No way to catch regressions
  • Can't compare models systematically
  • Stakeholders can't review prompt quality

With PromptLens

  • Automated test suites run on every change
  • Pass/fail thresholds block bad releases
  • Visual diffs catch regressions instantly
  • 25+ models tested in one click
  • Shareable reports for the whole team
Features

Everything you need to ship prompts safely

A purpose-built toolkit for teams who need prompt QA they can trust.

Regression Suites

Build test datasets with expected outputs. Run them on every prompt change to catch regressions before they ship.

Quality Scoring

Set pass/fail thresholds for your evals. Block releases that don't meet your quality bar automatically.

Version Comparison

See exactly what changed between prompt versions. Visual diffs show where outputs broke and why.

Model Matrix

Test the same prompt across OpenAI, Anthropic, and Google side-by-side. Find the best model for your use case.

Shareable Reports

Generate links for PRs, Slack, or stakeholder reviews. Everyone can see test results without an account.

How it works

Three steps to confident releases

Paste your prompt, add test cases with expected outputs, and run evaluations to get pass/fail results in minutes.

1

Paste your prompt

Add your system prompt and configure the model.

2

Add test cases

Define inputs and expected outputs.

3

Run and share results

Get pass/fail results, share with your team.

Built for teams, not MLOps engineers

PromptLens replaces manual prompt checking with automated regression testing. Just paste your prompt, add test cases, and share results.

No YAML configuration
No CLI to install
No infrastructure to manage
Prompt Regression Testing
Automatically re-running a suite of test cases against a prompt after every change to detect quality drops before deployment.
Evaluation
A single run of all test cases in a dataset against a specific prompt version and model, producing a pass/fail score.
Pass/Fail Gate
A quality threshold that blocks a prompt change from shipping if the evaluation score falls below the defined baseline.

One month from now

You'll stop eyeballing outputs and start actually testing them.

You'll catch regressions before they hit production.

You'll share results in PRs instead of Slack back-and-forth.

Start your first month
Pricing

Simple, transparent pricing

Start free with 3 projects and 50 evaluations per month. Upgrade to Pro at $99/month for unlimited projects, evaluations, and team access.

Free
$0
Best for trying out PromptLens
  • 3 projects
  • 50 evaluations/month
  • 3 share links
  • All LLM providers
Get started
Recommended
Pro
$99/month
For teams shipping LLM features
  • Unlimited projects
  • Unlimited evaluations
  • Unlimited share links
  • 10 team members
  • Version comparison
Start testing free
FAQ

Frequently asked questions

Common questions about setup, model support, pricing, and how PromptLens fits into your existing workflow.

Start testing your prompts today

No credit card required. Set up in 5 minutes.

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