Private Beta — 2026

evalOS

Ship AI changes with evidence, not vibes.

One line of code turns on OpenTelemetry-native observability, calibrated evaluation, and human-in-the-loop quality gates — from dev through production.

evalos — checkout-agent / production live
Quality — last 14 runs
gate ≥ .85−22% regression caught
Score
0.91quality
Judge scores · this run
faithfulness
0.94
answer_relevance
0.91
verbosity
0.62flagged
toxicity
0.02
gatePASS
cost / run$0.0042
driftnone
One OTel SDK captures
OpenAIAnthropicvLLMLangChainLlamaIndexPineconepgvectorPostgresGPUs
Every way it breaks

Production AI fails quietly. evalOS makes the failures loud.

Hallucinations, regressions, drift, cost blowouts, jailbreaks, runaway verbosity — surfaced, scored, and flagged before a user ever runs into them.

caught

Hallucination

Ungrounded claim, not in retrieved context.

faithfulness 0.48
caught

Regression

Prompt v4 quietly dropped quality vs v3.

−22% vs last release
caught

Drift

Input distribution shifted off the golden set.

KL 0.31 · shifting
caught

Cost spike

Retries tripled token spend per call.

$0.004 → $0.012
caught

Jailbreak

Adversarial probe slipped past the guardrail.

probe #318 · breached
caught

Verbosity

Answers padded well past what users read.

verbosity 0.62
The loop

Instrument once.
Improve forever.

evalOS sits on an OpenTelemetry foundation, so it captures everything — LLMs, vector DBs, even GPUs — from a single SDK. Every run feeds the next.

01
Instrumentone line of code
02
ObserveOTel-native traces
03
EvaluateAI agents + datasets
04
JudgeJudgeLM scoring
05
Analyzedashboards + cost
06
Improveship with evidence
What you get

One platform, the whole eval stack.

Not a dashboard bolted onto logs. Tracing, evals, judges, cost, and quality gates run on the same OpenTelemetry trace — so the number you ship on is the number you measured.

Analytics dashboard

Latency, throughput, and quality trends across every run.

Cost tracking

Per-call spend by model — including your own deployments.

gpt-4o
$0.0042
claude-3.5
$0.0031
llama-70b
$0.0006

Prompt Hub & versioning

Version prompts, diff changes, tie each edit to a score delta.

@@ system prompt · v3 → v4 @@
- Answer the question.
+ Answer using only the retrieved context.
+ If unsure, say you don't know.
faithfulness +0.07 · verbosity −0.15

JudgeLM, calibrated

Position-swapped LLM judges across model families, with consensus and agreement.

gpt-4o
0.92
claude-3.5
0.94
gemini-1.5
0.91
pos-A · pos-B (swapped)consensus 0.93 · agree

OpenTelemetry-native tracing

Every span — retriever, LLM, tool — captured from one SDK.

POST /chat
1840ms
retriever.query
410ms
pgvector.search
220ms
llm.chat gpt-4o
1130ms
tool.lookup_order
290ms

Exceptions monitoring

Catch failures and bad outputs before users report them.

EvalGround playground

Prototype evals and judges against live production traces.

API keys & secrets

Scoped keys and managed secrets for every environment.

evalOS Index

Rank models on your suite — not a vendor's leaderboard.

Public benchmarks don't run your prompts, your tools, or your data. evalOS scores every model on the tasks you actually ship, with cost and latency sitting right next to quality.

Switch the suite — coding, agents, RAG — and the ranking changes. The right model is the one that wins on your work.

evalOS Index · by suite
#model$/1kp50
1claude-opus-4.8$9.01.2s
2gpt-4o$5.00.9s
3claude-3.5-sonnet$3.00.8s
4gemini-2.0-pro$4.21.0s
5llama-3.1-70b$0.60.7s
preview · illustrative sample dataquality = composite judge score
Instrument once

Two lines. Then everything is observable.

No SDK sprawl, no per-vendor adapters. Drop in the import, name your service, and every LLM call, tool, and vector query starts streaming as OpenTelemetry spans.

app.py
trace · POST /chat1,840ms

// the spans that show up — automatically

POST /chat
1840ms
retriever.query
410ms
pgvector.search
220ms
llm.chat gpt-4o
1130ms
tool.lookup_order
290ms
The science behind the score

Not vibes-based grading. Published eval science.

evalOS implements the methods peer review trusts — so your scores hold up when an auditor, a board, or a skeptical engineer asks exactly how you got them.

RRD

Recursive Rubric Decomposition

Coarse rubrics decomposed into fine-grained, correlation-filtered sub-criteria with whitened-uniform weights.

arXiv:2602.05125
J1

Verifiable Rewards

Turns subjective judgments into verifiable preference pairs for GRPO judge training.

Meta · arXiv:2505.10320
JudgeLM

Trained, calibrated judges

Custom judge models trained with GRPO / LoRA and validated on RewardBench — not an off-the-shelf prompt.

RewardBench
Bloom

Behavioral evaluation

4-stage behavioral probing — understand, ideate, rollout, judge — with bootstrap CIs and Wilcoxon tests.

pass@k · bootstrap CI
// + benchmark adapters: HumanEval · MBPP · SWE-Bench Lite · GAIA · BigCodeBench
Why you can trust the number

Position-swapped

Every judgment is run with options swapped to cancel order bias.

Calibrated

Judges are tuned against human labels and checked on RewardBench.

Golden sets + drift

A held-out reference set flags when production drifts away from it.

Statistically honest

Bootstrap confidence intervals and Wilcoxon tests, not single-run noise.

Where it fits

Logs tell you what happened. evalOS tells you if it was any good.

Logging / APM
Notebook evals
Vendor self-grade
evalOS
OpenTelemetry-native tracing
Calibrated, position-swapped judges
Regression gates in CI
Cost + latency beside quality
Drift detection on live traffic
Runs in production, not just offline
Open standard · no lock-in
full partial none
Questions

What stage is evalOS at?

Private beta. We're onboarding a small number of teams running production AI — not a waitlist for a landing page.

What does it instrument?

Anything OpenTelemetry can see: LLM calls, vector DBs, tools, even GPUs — captured from a single SDK, no per-vendor wiring.

How is this different from an LLM-as-judge script?

The judges are calibrated, position-swapped, and trained (GRPO/LoRA) against RewardBench — and they run on the same OpenTelemetry trace as your production traffic, with drift detection and CI gates around them.

Hosted or self-hosted?

Early-access teams start on a managed workspace. Self-hosting is on the roadmap for teams with data-residency needs.

How do I get access?

Book a short call. If your AI is in production and you're guessing whether the last change helped, you're exactly who this is for.

gate: PASS

Stop shipping blind.

evalOS is in private beta. We're onboarding teams running production AI who are tired of guessing whether their changes made things better or worse.

Request early access

Or email rachitt@transfrm.in — response in 48h, no sales process

Transfrm Labs
by Rachitt Shah

Applied AI systems, production-grade. Building with teams at Accel, Sequoia, and friends. Bangalore · San Francisco.

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