universal evaluator api // powered by typesafe jev

Every evaluator.
One call.

jeval runs the evaluators you already use from autoevals, RAGAS, UiPath and promptfoo as calibrated Jev judgments. Send input, output, expected and context once; get every score, probability and confidence back in a single request, in a few hundred milliseconds, for a fraction of a cent.

Fig 1 · one item in, one request out, every evaluator in the suite read at once; pick a suite or use keys 1–3.
Evaluators
60
38 answered by Jev, 22 in code
Requests per item
1
every evaluator fans out in one call
Typical latency
~200ms
measured, 6-evaluator RAG suite
Typical cost
$0.00004
per item, output tokens free
Cheaper than an LLM judge
272×
on the bundled benchmark
what it does // how it works

Evals are decisions, not paragraphs.

An LLM judge writes reasoning and then a number. You pay for the reasoning, wait for it, parse it, and get a point estimate with no calibration. Jev never generates text: it reads your state once and returns a probability distribution for every question in the request. jeval maps each evaluator to those questions and combines the answers in code, so the policy is visible and the numbers are comparable.

swap the answer // live distribution
input
What is Jev's context limit?
context
Context length: 64k tokens per request; 32k for state plus the longest question.
output
64k tokens per request; 32k for state plus the longest question.
  • faithfulness0.00pass
  • answer_relevancy0.00pass
  • context_precision0.00pass
1 request, 0 ms, $0.00003Sample output. Run your own
request
curl -X POST https://jeval.dev/api/v1/evaluate \
  -H 'authorization: Bearer jv_…' \
  -H 'content-type: application/json' \
  -d '{
    "suite": "rag",
    "input": "What is Jev's context limit?",
    "output": "64k tokens per request; 32k for state plus the longest question.",
    "context": ["Context length: 64k tokens per request; 32k for state plus the longest question."]
  }'
Fig 2 · one relevance probability and one verdict per retrieved chunk; pick a chunk or use the arrow keys.
Grounding, per chunk

Every chunk gets its own verdict.

Relevant or not, supports or contradicts: one probability per retrieved chunk, in the same request as faithfulness, precision and recall. Contradicting chunks are the hallucination signal, per chunk instead of a paragraph.

Try it in the playground
Fig 3 · one yes/no probability per expected step, and a semantic check on the tool call; use the arrow keys.
Agents, per step and per call

Trajectories and tool calls, judged semantically.

UiPath's trajectory and tool-call judges re-expressed as one yes/no probability per expected step and per expected call. Renamed argument keys and reformatted dates stop counting as failures.

See why Jev fits
Fig 4 · drag the gate: the scores never change, only which side of it they fall on.
Probabilities, not prose

Decisions you can threshold.

Each result carries a distribution over rubric levels and a confidence. Set your own cut-offs in code, change them without re-running inference, and never parse a paragraph again.

Read the API reference
Cost, per item

One request instead of one judge call per evaluator.

An LLM judge is called once per evaluator, reads a prompt template on top of your data each time and writes its reasoning before the verdict. Jev reads the item once, answers every question in the same request and generates nothing, so you pay for input tokens only.

Jev requests
1
Judge calls
6
Sample gap
494×
Run the benchmark
Fig 5 · one Jev request against one judge call per evaluator; change the evaluator count to see the gap.
faq // answer first

Questions, answered first.

Short, direct answers. The same ones an answer engine should be able to quote.

jeval is a universal evaluation API. It exposes the evaluators from autoevals, RAGAS, UiPath's eval library and promptfoo's assertion set through one endpoint, and answers the judgment-based ones with TypeSafe's Jev model instead of an LLM prompt. You send input, output, expected and context; you get back a score, a probability distribution, a confidence and a pass/fail for every evaluator you asked for, in one request.

get started // no sign-up

Run your first evaluation in the next minute.

No sign-up. Free key. Real numbers on screen.