Agent Control Panel vs Langfuse and LangSmith
Langfuse and LangSmith are LLM observability and evaluation platforms: they record detailed traces of what your agents did and help you measure quality. Agent Control Panel (ACP) is a control panel for operating agents already in production: it monitors runs, cost and health per agent, and lets you pause, stop, switch models or roll out approved prompts without redeploying. Many teams will want both.
Side by side
Based on each product’s own website and documentation, checked October 4, 2026. Features change; follow the links for the current state.
| Langfuse | LangSmith | Agent Control Panel | |
|---|---|---|---|
| Main job | LLM engineering: tracing, evaluation, prompt management | Agent observability, evaluation and deployment | Operating agents in production |
| Detailed traces of each run | Yes, hierarchical traces | Yes | Run records (input, output, tokens, model, errors); not a step-by-step tracer |
| Evaluations | LLM-as-a-judge, human annotation, experiments | Online LLM-as-judge and code evals | AI quality reviews of real runs; Testing Lab for prompt and skill changes |
| Cost tracking and alerts | Cost and latency dashboards, alerts | Cost tracking; webhook and PagerDuty alerts | Cost per agent; spend-cap, error-rate, anomaly and lost-heartbeat alerts |
| Change a prompt without redeploying | Yes, versioned prompts your code fetches | Prompt engineering tools | Yes, with owner or admin approval against the current version |
| Switch an agent’s model without redeploying | Not described | Fallback chains through its LLM Gateway (OpenAI-compatible and Anthropic models) | Yes, per agent, from the dashboard, any provider |
| Pause or stop a running agent | Not described | Not described | Yes: manual, or automatic on alert rules |
| Liveness of each agent | Not described | Not described | Heartbeats every 30 seconds |
| Open source | Yes (MIT), self-hostable | No; self-hosted and BYOC options | SDKs are open source (Apache-2.0); the platform is hosted |
| SDKs | Python and TypeScript, more via OpenTelemetry | Python, TypeScript, Go, Java | Node.js and Python |
“Not described” means we did not find the feature on the product’s website or documentation. It is not a claim that the product cannot do it.
Which one do you need?
- You are building and debugging an agent and want to see every step, compare prompts on datasets and score quality: start with an observability platform such as Langfuse or LangSmith.
- Your agents already serve users and you need to stop one in seconds, move it to another model during an outage, cap its daily spend, or let someone other than its developer act on it: that is what Agent Control Panel is for.
- Both is common. ACP’s SDK wraps your model call and reports runs; a tracing SDK can instrument the same code. They do not depend on each other.
What is different about how Agent Control Panel works
- Beside the call, not in it. Your agent calls its provider directly with your own keys. Nothing proxies your model traffic.
- Fail-open. If ACP is unreachable, your agents keep running.
- Signed, scoped commands. HMAC-SHA256 with a timestamp and single-use nonce. New apps start in monitor-only scope.
- Durable control. A pause or model swap set in ACP survives restarts and extra replicas, because every heartbeat reply carries the state ACP holds.
Next: add a kill switch, switch models without redeploying, or connect an existing app.
Frequently asked questions
Is Agent Control Panel a Langfuse alternative?
Partly. Both record runs and cost, but Langfuse focuses on tracing, evaluation and prompt management, while ACP focuses on operating agents in production: pausing, stopping, switching models and approved prompt changes. Many teams use an observability tool and ACP together.
Is Agent Control Panel a LangSmith alternative?
Not a replacement for LangSmith’s tracing and evaluation. ACP adds control of running agents (pause, stop, per-agent model swap, automatic pause on spend or errors) and works with any framework.
Can I use Agent Control Panel with Langfuse or LangSmith?
Yes. ACP’s SDK wraps your model call and reports runs; it does not replace or conflict with a tracing SDK.
Is Agent Control Panel open source?
The Node.js and Python SDKs are open source under Apache-2.0. The control panel itself is a hosted service.
Related guides
- What is an AI agent control panel?: How it differs from a control plane, observability, gateways and orchestration frameworks.
- Switch an AI agent’s model without redeploying: Move an agent to another model, or another provider, in seconds, and what to check first.
- How to monitor AI agents in production: The signals that matter (liveness, errors, cost, quality) and what to do when one moves.
- Roll out a new AI agent prompt safely: Versioning, review, approval, testing and rollback for prompts in production.
- Daily spend caps and automatic pause for AI agents: Stop runaway token spend before the invoice: caps, loop detection and safe defaults.
- What is an agent control plane?: How it differs from observability and gateways, and when you need one.
- AI agent kill switch: How to stop or pause an agent in production, and what a trustworthy switch needs.
Next: connect an existing app, read the documentation, or request early access.