An honest look at every alternative. Not because they are bad products — but because they were not built for this problem.
Built from the first line for the MCP protocol and AI agent governance. Every feature exists because agents need it, not because it was already in the product when the pivot happened.
Excellent for routing HTTP traffic. Built before LLMs existed. They understand methods and paths, not "this tool call might delete a production record and should require approval." You can bolt on AI features, but you will spend months doing it.
Strong observability for LLM calls. Cannot intercept tool calls in the request path. Data travels to an external cloud. No policy enforcement. No approval gate. Good for tracing; not a substitute for a control plane.
Every enterprise AI team tries this. The best ones get to 70% and ship. The ones that get to 100% discover they have a new full-time infrastructure product to maintain. Synapse Relay is the 100% that already exists.
| Capability | Synapse Relay | Kong / Apigee | Langfuse / Braintrust | Build Yourself |
|---|---|---|---|---|
| MCP protocol support | ✓ Native, first-class | ✗ HTTP only | ⚬ Logging only | ⚬ You build it |
| Zero per-token cost | ✓ Self-hosted vLLM | ✓ Not applicable | ✗ Per-event pricing | ⚬ Depends on choice |
| Data never leaves VPC | ✓ Everything on-prem | ✓ Self-hosted option | ✗ Cloud-only default | ✓ If designed right |
| PII redaction in request path | ✓ Presidio + regex fallback | ✗ | ⚬ Post-hoc masking only | ⚬ 4–8 weeks of work |
| Human approval gate | ✓ Destructive call hold | ✗ | ✗ | ⚬ Complex to build right |
| OPA policy enforcement | ✓ Per-call, in-path | ⚬ Plugin, HTTP only | ✗ | ⚬ Wire it yourself |
| MCP server auto-generation | ✓ OpenAPI / Postgres / GitHub | ✗ | ✗ | ✗ |
| One-click connector import | ✓ Composio + Zapier NLA | ✗ | ✗ | ✗ |
| Real-time WebSocket dashboard | ✓ Built-in, live feed | ⚬ Third-party needed | ✓ Managed | ⚬ Build it |
| Kubernetes + Helm | ✓ Full chart, GPU support | ✓ Mature | ⚬ Basic | ⚬ You write manifests |
| Multi-tenant RBAC | ✓ 4 roles, full isolation | ✓ Enterprise tier | ⚬ Limited | ⚬ Weeks of work |
| Open source license | ✓ Apache 2.0, full platform | ⚬ Open core | ⚬ MIT (limited) | ✓ It's yours |
| Time to first governance | ✓ 1 command, ~2 minutes | ⚬ Days to weeks | ⚬ Hours | ✗ 6–12 months |
| HIPAA/SOC2 readiness | ✓ All data on your infrastructure | ⚬ Possible, complex setup | ✗ Data leaves boundary | ⚬ If architected correctly |
These are world-class products for routing HTTP traffic. If your problem is "I have a REST API and I need rate limiting, authentication, and basic analytics," they are excellent choices and you should not replace them with Synapse Relay. The moment your problem becomes "I have AI agents making tool calls and I need to govern every action they take," these products reach their design boundary. You will spend months building plugins, custom middleware, and workflow integrations to get a fraction of what Synapse Relay ships with on day one. They were not built for this.
These products are excellent at what they were designed for: tracing LLM calls, comparing prompt versions, and providing a management interface for language model experiments. They operate as observers, not interceptors — they see what happened after the fact, not in the request path. They cannot enforce a policy. They cannot hold a tool call pending approval. They cannot redact PII before it reaches a log. And critically, they are managed cloud services: your agent's data travels to their infrastructure as a fundamental part of the product model. For enterprises in regulated industries, this is a non-starter, full stop.
Every team that tries to build this discovers the same things in roughly the same order. First: the happy path is easy. Second: PII detection is surprisingly hard to get right at low latency. Third: the approval workflow has more edge cases than you thought (what happens when the reviewer is offline? what about expiry? what about retries?). Fourth: multi-tenancy touches every layer of the stack. Fifth: you have now spent nine months on infrastructure and you have not shipped a single feature for your actual product. Synapse Relay is the result of solving all of these problems once, correctly, and making it free. The only valid reason to build it yourself is if you have requirements that are genuinely different from what this platform provides — and in that case, the Apache 2.0 license means you can fork it and own the delta.