The best way to do AI evals

Get the right output,
first time, every time

Stop tweaking system prompts on vibes. eval.dog systematically tests every version of your prompt against real cases and real criteria — so you know what actually improved.

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Free plan included. No credit card required.

Build AI systems you can trust

Measure, refine, and perfect your system prompts with a scientific approach to evals — minus the spreadsheet drudgery.

Versioned prompts

Every edit creates an immutable version. Nothing is ever lost, and every run is traceable to the exact prompt that produced it.

Reusable criteria

Define what a good output looks like once — "stays in persona", "no hallucinated facts" — weight it, and reuse it across prompts.

One-click eval runs

Run every test case against your prompt and watch results stream in live. An LLM judge scores each output against each criterion, 0–10, with a rationale.

Version comparison

See criterion-by-criterion scores across versions side by side, so you know whether that prompt tweak actually helped.

Scores you can act on

Weighted case scores roll up into an aggregate grade. 9+ is Best in Show. Below 7? Needs Training.

Playfully rigorous

Evals shouldn't feel like homework. eval.dog makes them fast and fun enough that you'll actually do them daily.

How it works

From vibes to verified in four steps.

1
Paste your system prompt
Create a prompt, pick the target model, and you're versioned from the first save.
2
Add test cases & criteria
Type test inputs or import a CSV. Attach the criteria that define success for this prompt.
3
Run the eval
Each case runs against your prompt, then an LLM judge scores every output against every criterion.
4
Compare and improve
Tweak the prompt (new version!), run again, and watch the scores move. Ship when it's Best in Show.

Simple, honest pricing

An execution is one test case run, judging included. Start free, upgrade when your evals do.

Free

Kick the tires. No card required.

$0 / month

2 prompts
50 eval executions / month
Unlimited criteria & test cases
Version comparison

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Pro

Team

For teams that eval every day.

$99 / month

Everything in Pro
10,000 eval executions / month
Priority support

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Your prompts deserve better than vibes

Set up your first eval in under five minutes. Your future self — and your users — will thank you.

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Get the right output,first time, every time