by Axiom Studios

Your AI Prompt,
Evolved.

Evolution Arena uses battle-tested AI to make your system prompts stronger. Submit, battle, evolve.

Try it free — no code needed See how it works
+5.7
Avg score lift
3
Battle rounds
~$0.005
Cost per run
137
Tests passing
How it works

Evolution, not trial and error.

Most prompt engineering is guesswork. We apply structured selection pressure — the same mechanism that's been producing better results for 3.8 billion years.

📝
Step 1

Paste your prompt

Drop in your current system prompt and a couple of questions that represent how you actually use it.

⚔️
Step 2

Battle it out

Two variants of your prompt compete on your questions. They respond, rebut, and get scored by an impartial AI judge.

🧬
Step 3

Survival of the fittest

The winner survives. The best ideas from the loser get absorbed. A stronger version enters the next round.

Step 4

You get a better prompt

All battle learnings distilled into one clean, improved prompt. Ready to drop in wherever you need it.

⚖️ How we judge

Every battle round is scored by an independent AI judge on 5 criteria:

Total: 50 points per agent per round. The stronger prompt wins the round.

Before vs. after. Real battles.

Actual outputs from real runs — not hand-picked examples. Click a demo below to explore the results.


⚙️ For developers

Clean REST API. Two calls.

Submit and poll. No SDKs required — just standard HTTP. Integrate prompt evolution directly into your CI/CD or agent pipelines.

POST /optimize
# 1. Submit your prompt
curl -X POST /optimize \
  -H "Content-Type: application/json" \
  -d '{
  "system_prompt": "You are a support agent...",
  "test_questions": [
    "My order is 2 weeks late",
    "I want a refund now"
  ],
  "n_rounds": 3
}'

# Returns immediately:
{
  "job_id": "a3f9b2...",
  "status": "pending"
}
GET /jobs/{id}
# 2. Poll for results
curl /jobs/a3f9b2...

# When done:
{
  "status": "done",
  "result": {
    "winner_prompt": "You are a support
    agent who leads with
    empathy, then resolution...",
    "score_delta": 6.3,
    "improvement_notes": "...",
    "rounds": [...]
  }
}
OpenAPI docs → GitHub →

Pricing

Start free. Scale when you're ready.

No surprises. A 3-round optimization costs fractions of a cent in API calls.

Free
$0
No card required. Try the full thing.

  • 3 runs / day
  • Haiku model only
  • Up to 10 runs / month
  • Full battle logs
  • API access
Get Started →
Pro
$29 / mo
For power users and production workloads.

  • 50 optimizations / day
  • All models including Opus
  • 5 rounds per run
  • Full API access
  • Priority support
Pay-as-you-go
No commitment, no subscription
$0.05 / run
No subscription. Just pay for what you use.
  • Unlimited runs
  • 5 rounds per run
  • Full API access
  • No monthly commitment