Both trace agents, run offline and online evals, queue runs for human review and version prompts, and both charge per seat. LangSmith is the pick for teams on LangChain or LangGraph that start from production traces; Maxim AI suits teams that want to simulate text and voice agents before launch and run a gateway that can check tool calls.[1][4]
LangSmith is LangChain's platform built around traces and the LangChain stack, while Maxim AI is built around simulating agents, including voice agents, before release, sold alongside Bifrost, its Apache-2.0 AI gateway. Both price per seat, both trace and evaluate agents, and both are independent. Maxim's Bifrost gateway can check MCP tool calls; LangSmith's gateway covers model calls only.
| Decision factor | LangSmith | Maxim AI |
|---|---|---|
| Ownership | LangChain, independent; $125M Series B in October 2025 | Independent (H3 Labs Inc.); $3M seed led by Elevation Capital in 2024 |
| Starting point | Production traces, curated into datasets | Pre-release simulation of multi-turn text and voice agents |
| Gateway | LLM Gateway (beta): spend caps, model access and redaction on model calls | Bifrost (Apache-2.0): failover, caching, budgets, MCP gateway |
| Run-time checks on tool calls | No; tool and MCP gateways described as planned | Yes, via Bifrost guardrails on MCP tool calls (Bifrost Enterprise feature) |
| Online evals | Yes, on every plan including the free tier | Yes, from the Professional plan upwards |
| Self-hosting | Enterprise add-on on Kubernetes; BYOC also Enterprise | Platform: Enterprise in-VPC only. Bifrost OSS: free to self-host |
| Free tier | Developer: 1 seat, 5k base traces a month, 14-day retention | Developer: up to 3 seats, 10k logs a month, 3-day retention |
| First paid tier | Plus: $39 per seat a month, 10k base traces | Professional: $29 per seat a month, 100k logs, 7-day retention |
| Capability | LangSmith | 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 | Partial | ✓ | ✓ |
| Gateway or proxy in the request path | — | ✓ | — |
| Licence and deployment | |||
| Open source | Partial | Partial | Partial |
| Self-hosting | ✓ | ✓ | Partial |
Maxim's distinguishing feature is simulation. It runs multi-turn conversations against prompts, no-code agents or agents behind an HTTP endpoint, including voice agents, and scores them with agent evaluators such as trajectory, tool selection and task success. Test runs can be scheduled or triggered from GitHub Actions. Product and engineering staff can both work in it, which is how Maxim positions the product.
LangSmith starts from the trace. You instrument, add interesting production runs to datasets and grow experiments from what you see; Engine, in public beta, reads those traces and drafts fixes. Its deepest integrations are with LangChain, LangGraph and Deep Agents, and LangSmith Deployment runs those agents. LangSmith supports offline experiments and backtesting but does not document voice simulation.
Both run evaluation after release too. Maxim evaluates production logs at session, trace and node level with sampling and alerts to Slack and PagerDuty, from the Professional plan upwards. LangSmith runs online evaluators on every plan, through automation rules with filters and sampling. Both have annotation queues; Maxim added external raters by email in January 2026.
Both vendors sell a gateway, with different reach. Maxim's Bifrost is an open-source, Apache-2.0 gateway with provider failover, load balancing, semantic caching, budgets per virtual key and an MCP gateway. Its guardrails check inputs, outputs and MCP tool-call arguments and results, and can block, redact or transform them, but guardrails are listed as a Bifrost Enterprise feature. The Maxim evaluation platform itself alerts rather than blocks.
LangSmith's LLM Gateway, in public beta since 30 July 2026, covers model calls only: spend caps, model access policies and redaction. LangChain describes tool and MCP gateways as planned. If you need checks on what an agent sends to its tools today, Bifrost reaches further, provided you buy its Enterprise edition.
Bifrost can be self-hosted with Docker, Kubernetes or a Go binary, and its Enterprise edition runs in a VPC, on premises, air-gapped or hybrid. That makes it usable as a gateway even if you trace and evaluate elsewhere.
LangSmith publishes a dated changelog with entries through October 2026, including new plans, Engine v2, the Trajectory view and gateway changes. Maxim's public product changelog shows no dated 2026 entries, and its newest monthly update post covers December 2025, so recent platform changes are hard to verify. Bifrost, by contrast, published release v2.3.1 on 19 October 2026.
In October 2026 Maxim's homepage and main pricing page began leading with Bifrost, and the evaluation platform moved under getmaxim.ai/evals. Neither change says anything about the evaluation product's future, but ask about its roadmap during a trial.
Prompt work is similar on both: Maxim has a playground, versions, deployment rules that release prompt changes without code changes, and prompt optimisation. LangSmith has a Prompt and Context Hub with commit-based versions, tags and a playground.
Both charge per seat. As of 20 October 2026, LangSmith's Developer tier is free for one seat and 5k base traces a month, and Plus is $39 per seat a month with 10k base traces; the per-trace overage rate is not published. Maxim's Developer tier is free for up to three seats and 10k logs a month with 3-day retention, Professional is $29 per seat a month with 100k logs, and Business is $49 per seat a month with 500k logs, with overage at $1 per 10k logs. Bifrost OSS is free. Check LangSmith's pricing and Maxim AI's pricing against your own volumes.
Retention is short at the low end of Maxim's tiers: 3 days on Developer, 7 on Professional and 30 on Business. LangSmith keeps base traces for 14 days on every plan, with extended retention up to 180 days.
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 on tool calls and data access, approval holds for risky actions, and a kill switch for a run, an agent or a team. Maxim's Bifrost Enterprise can block or redact MCP tool calls; LangSmith's gateway covers model calls only; neither documents approval holds. Prefactor has no simulation, gateway, prompt playground or prompt registry, and it is hosted. 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.