Stop guessing which prompt is better

You changed a prompt, skimmed a few outputs, and shipped it — hoping. LLMJury runs the test for you on real traffic, grades the answers automatically, and tells you plainly which variant wins. Proof, not gut feeling.

Free plan · no credit card required

Sound familiar?

You pick prompts by eyeballing ten outputs

You tweak a prompt, skim a handful of answers, and the new one “feels better.” Ten examples can look great while the change quietly makes half your real traffic worse.

Model upgrades are a coin flip

A new model version drops and you switch, hoping nothing breaks. Without measuring on your own traffic, you find regressions the way your users do — after they happen.

“Are you sure?” has no good answer

When a teammate or launch review asks how you know the new prompt is better, “I looked at some outputs” is the whole case. There is no number to point at.

LLMJury replaces “it feels better” with a measured answer from your own users — without you touching a statistics textbook.

From gut feeling to verdict in three steps

1

Wrap your model call

Two lines with our Python, TypeScript, or Java SDK. Your prompt and model variants live behind one key — change them without redeploying.

2

Let real traffic vote

Each user is consistently assigned to a variant. LLMJury grades a sample of the outputs automatically and tracks speed, cost, and conversions alongside.

3

Read a plain verdict

“Variant B wins on quality, ties on speed, costs 12% less.” Trustworthy math underneath, plain words on top — and a result you can defend in any review.

Everything you need to ship LLM changes with confidence

Test prompts and models on real traffic

Swap prompts, models, or parameters behind a variant key — no redeploys. The same user always sees the same variant, in every SDK, so the comparison is fair.

Test prompts and models on real traffic. Swap prompts, models, or parameters behind a variant key — no redeploys. The same user always sees the same variant, in every SDK, so the comparison is fair.

An LLM-as-judge scores your outputs for you. Built-in quality, safety, and relevance grading — plus your own rubric in plain English. Sampled and budget-capped, so grading never runs away with your bill.

Broken tests get stopped, not shipped. If your traffic split breaks, LLMJury halts the analysis instead of showing you a lie. Every result is checked against false positives before it reaches you. The full statistical detail is always one click away.

See if “better answers” actually moves the business. Send conversions or revenue events and read them next to quality scores — one experiment, one verdict, in the same place.

LLM-as-judge grading with SRM-gated, FDR-corrected statistics for defensible results.

Tour the product

Works with the stack you already use

  • OpenAI
  • Anthropic
  • LangChain
  • LlamaIndex
  • Vercel AI SDK
  • LiteLLM

Start free — no credit card required

Free gets you real experiments on 50k events a month. Upgrade for automatic quality grading and team seats; see full pricing.

Free

$0/mo

Run your first real experiment and see the difference proof makes.

  • 50k events/mo
  • 1 seat
  • Latency, cost & business metrics
  • 7-day raw-event retention
  • All 3 SDKs (Python, TypeScript, Java)
  • Traffic-split safety check
  • Unlimited experiments

Pro

Most popular

$149/mo

+$49 per extra 500k events

For teams shipping LLM features who need automatic quality grading.

  • 1M events/mo
  • 10 seats
  • LLM-as-judge · 50k evaluations/mo
  • 30-day raw-event retention
  • Everything in Free
  • Custom judge metrics
  • Email support

Business

$799/mo

+$99 per extra 2M events

For production-scale products and larger teams.

  • 10M events/mo
  • 50 seats
  • LLM-as-judge · 500k evaluations/mo
  • 90-day raw-event retention
  • Everything in Pro
  • Method overrides
  • Priority support

Enterprise

Coming soon

Custom

Custom limits, security review, SSO, and a dedicated contact.

  • Custom allowance
  • Custom seats
  • Custom judge budget
  • Configurable retention
  • Custom limits
  • Security review
  • Dedicated support

2 lines

of code to put your first experiment live

3 SDKs

Python, TypeScript, Java — identical assignment everywhere

1 verdict

quality, speed, cost, and business impact in one answer

Want to shape the product?

We are taking on a few design partners: 6 months of the Business plan free, direct access to the founders, and your needs driving the roadmap.

Become a design partner

Questions? Talk to us.

Email [email protected] or book a live demo — we answer everything ourselves, within one business day.

Contact us

Your next prompt change, proven

`pip install llmjury`, wrap your model call, and your first experiment is live — free, no credit card.

Free plan · no credit card required