Both are hosted platforms with tracing, offline experiments, online scoring, human review and prompt versioning. Braintrust centres on experiments, with an in-product agent that reads results and suggests changes; Maxim AI centres on simulating conversations with your agent, text or voice, and pairs it with an open-source gateway. Team size and how you want to pay often settle it.[1][4]
Braintrust and Maxim AI are both hosted, proprietary evaluation platforms; the difference is that Braintrust is organised around experiments and an analysis agent, while Maxim AI is organised around simulating agents, including voice agents, before release. Maxim AI also sells Bifrost, an Apache-2.0 gateway whose Enterprise edition can block content. Braintrust charges a platform fee with unlimited users; Maxim AI charges per seat.
| Decision factor | Braintrust | Maxim AI |
|---|---|---|
| Ownership | Independent; $80M Series B in February 2026 | Independent; $3M seed led by Elevation Capital in 2024 |
| Centre of gravity | Experiments: dataset, task, scorers, compare, with the Loop agent | Simulation: multi-turn text and voice runs before release |
| Gateway | Hosted gateway in public preview, free, no SLA | Bifrost: Apache-2.0, self-hosted, with a paid Enterprise edition |
| Runtime guardrails | None; scoring and alerts run after logging | Through Bifrost Enterprise guardrails on inputs, outputs and MCP tool calls |
| Self-hosting | Enterprise only, data plane only; Braintrust runs the control plane | Enterprise in-VPC, fully isolated or data plane only |
| Free tier | Starter: 1 GB processed data, 10K scores, 14-day retention | Developer: up to 3 seats, 10k logs a month, 3-day retention |
| First paid tier | Pro: $249 a month, unlimited users | Professional: $29 per seat a month, 100k logs |
| Capability | Braintrust | Maxim AI | Prefactor |
|---|---|---|---|
| Observe | |||
| LLM call tracing | ✓ | ✓ | ✓ |
| Multi-step agent tracing (tool calls, nested spans) | ✓ | ✓ | ✓ |
| Cost tracking | ✓ | ✓ | ✓ |
| OpenTelemetry support | ✓ | ✓ | ✓ |
| Evaluate | |||
| Offline evals (datasets, experiments) | ✓ | ✓ | ✓ |
| Online evals on production traffic | ✓ | ✓ | ✓ |
| LLM-as-a-judge scoring | ✓ | ✓ | ✓ |
| Code-based evaluators | ✓ | ✓ | ✓ |
| Human review and annotation | ✓ | ✓ | ✓ |
| Prompt versioning and playground | ✓ | ✓ | — |
| Act on findings | |||
| Runtime controls on live agent actions | — | ✓ | ✓ |
| Gateway or proxy in the request path | ✓ | ✓ | — |
| Licence and deployment | |||
| Open source | Partial | Partial | Partial |
| Self-hosting | Partial | ✓ | Partial |
Braintrust's product starts from the experiment. You bring a dataset, define a task and scorers in TypeScript, Python or the UI, run variants and compare them. Its Loop agent reads project data, writes scorers and runs evals, and since September 2026 Patterns group production behaviour for review. Several of these newer features are in public preview, and workflow evals using provider batch APIs arrived in October 2026.
Maxim AI starts from the simulated conversation. It runs multi-turn simulations of text and voice agents, and test runs over datasets for prompts, no-code agents and agents behind an HTTP endpoint, with scheduled runs and a GitHub Actions integration. It also lists simulation for AWS Bedrock Agents and Glean agents. If your agent talks to customers, especially by voice, Maxim AI's starting point is closer to the problem. If you iterate on prompts and scorers against fixed datasets, Braintrust's loop is closer.
Both cover the other motion. Braintrust traces agent frameworks such as the OpenAI Agents SDK, LangGraph and LiveKit Agents; Maxim AI scores production logs at session, trace and node level.
Both vendors sell a gateway, and they are at different stages. Braintrust Gateway gives one API to OpenAI, Anthropic, Google, AWS and others with caching and logging. The hosted gateway is in public preview, free and has no SLA, and it can run inside a self-hosted data plane. It replaced Braintrust's earlier AI proxy, which is deprecated.
Bifrost, Maxim AI's gateway, is Apache-2.0 and self-hosts on Docker, Kubernetes or a Go binary. It offers provider failover, load balancing, semantic caching, virtual keys with budgets and rate limits, and an MCP gateway. In October 2026 it began leading Maxim AI's homepage, and release v2.3.1 was published on 19 October 2026. If you want to run the gateway in your own network today, Bifrost is the one that is open source and not labelled a preview.
Self-hosting the evaluation platforms is Enterprise only on both. Braintrust runs its data plane in your AWS, GCP or Azure account while it keeps operating the control plane, including the UI and authentication. Maxim AI deploys in your VPC on the same clouds, either fully isolated or as a data plane peered to its hosted control plane. If nothing may leave your network, only Maxim AI documents a fully isolated option.
Braintrust documents no blocking, guardrails or approvals on live agent actions. Its online scoring runs after logging, and alerts to Slack, PagerDuty or webhooks notify rather than stop anything. Loop asks for approval only for its own edits inside Braintrust.
Maxim AI's evaluation platform also observes rather than blocks, but Bifrost's guardrails check inputs, outputs and MCP tool-call arguments and results, and can block, redact or transform content. Guardrails are listed as a Bifrost Enterprise feature, so budget for that edition if run-time blocking is part of the reason you are choosing.
As of 20 October 2026, Braintrust's Starter tier is free with 1 GB of processed data, 10K scores and 14-day retention, and Pro is $249 a month with 5 GB and 50K scores, then $3 per GB and $1.50 per 1,000 scores. Every plan includes unlimited users. Maxim AI's Developer tier is free for up to 3 seats and 10k logs a month with 3-day retention; Professional is $29 per seat a month with 100k logs and 7-day retention, and Business is $49 per seat a month with 500k logs and 30-day retention. Overage is $1 per 10k logs.
On these terms, a team of up to eight on Maxim AI's Professional plan pays less than Braintrust Pro's platform fee before usage, and a larger team may find Braintrust's unlimited users cheaper. Self-hosting is Enterprise and custom on both. Check Braintrust's pricing and Maxim AI's pricing against your own seats and volumes.
We sell the layer this section describes. Read it with that in mind.
Stated plainly, since Prefactor publishes this page: Prefactor is an agent evaluation platform that scores each step of a run and acts on what it finds through runtime policies, approval holds and a kill switch scoped to a run, an agent or a team. Braintrust does not act during a run; Maxim AI can block content through Bifrost Enterprise guardrails, but documents no approval holds. Prefactor has no prompt playground or prompt registry and its platform is hosted, so if prompt iteration or a self-hosted gateway is the priority, Braintrust or Maxim AI is the better pick. See the full comparison of 15 platforms.
Reviewed against public product and documentation pages on October 20, 2026. If a vendor has changed a feature, product name, or positioning since then, send a correction and we will update it. Numbered source links in the page body point to the ordered sources below.
Prefactor scores each step of every agent run and can hold or stop an action when a score says it should not happen. Start on the free tier: 5,000 spans a month, no credit card required.
Prefactor helps teams observe, evaluate, and improve their AI agents in production, across every framework and provider.