They solve different halves of the same problem, and the honest summary is that a lot of teams should run both. Docker isolates the server: containers, signed images, no host filesystem. KnoxCall governs the call: who may reach which tool, with which token, and what may travel in the arguments.
Give them their due
Read from Docker's own docs and repo on 2026-08-25 — docs.docker.com and github.com/docker/mcp-gateway (MIT). If container-level isolation is what you are missing, this is the better tool and we would tell you so.
--verify-signatures, on by default.env path--block-secrets, on by default--block-network--servers, --tools, --profileWhere they differ
Each row cites both halves. Docker's column comes from the pages linked above; ours comes from the same code citations behind our honesty table. Where we could not evidence something about Docker, the row says so rather than assuming absence.
| Docker MCP Gateway | KnoxCall | |
|---|---|---|
| Server isolation | Containers, capped CPU/memory, no host filesystem, signed images | Not our layer — we proxy, we do not host |
| Token audience binding | OAuth flows are built in; a per-server audience binding is not among the seven features the README enumerates | RFC 8707: wrong resource is 401, unbound is 401 fail-closed, non-tool-bound is 403 |
| Empty tool allowlist | Filtering is opt-in via --tools / --servers; unset means unfiltered |
Empty advertises nothing; the caller's token intersects, never unions |
| PII / DLP on tool arguments | Not among the seven features the README enumerates, and absent from the Gateway docs page. --block-secrets is credential-pattern matching, not PII classification. Possible via --interceptor; no bundled PII plugin we could find |
Built-in detectors on arguments and results — SSN, PAN, IBAN, email, phone, JWTs, live provider keys. Custom and pack recognizers do not reach this path yet |
Prompt-injection policy on tools/call |
Could not evidence either way from the pages we read | A server can carry a firewall policy; a block policy refuses the call |
| Where org governance is sold | Docker AI Governance is "available on a separate paid subscription", GA 2026-05-12, and the Catalog page notes the gateway integration is invite-only | Same product, same bill, from the free tier |
| Multi-tenancy in the gateway itself | Could not evidence; the OSS gateway reads as a per-developer CLI and tenant-style isolation appears via the paid plane | Tenant is the primary key of everything; cross-tenant isolation is a CI guard, not a convention |
| Model traffic | Out of scope — it is an MCP gateway | Same gateway governs model calls: budgets, model policy, mid-stream PII redaction |
Docker is candid about its own posture, and we will quote it rather than paraphrase: its FAQ says the catalog's security measures "currently represent a best-effort approach… not yet exhaustive". That is a fair thing for a fast-moving catalog to say. It is also the reason a second layer — one that governs the call rather than the image — is not redundant.
Choosing
you are running third-party MCP servers on developer machines and your worry is what the server binary does — filesystem access, outbound network, supply-chain provenance. Container isolation and signed images are the right control for that, and we do not offer them.
your worry is what the agent does: which of your people's tokens can reach which tool, whether a stolen tool token opens more than one server, whether customer data is leaving in tool arguments, and whether you can answer an auditor's "who called what" a year later. And if the same answer needs to cover your model traffic, that is one gateway rather than two.
They compose: Docker isolates the server process, KnoxCall governs the calls reaching it. Nothing in either design conflicts with the other, and a page that told you otherwise would be selling rather than comparing.
Usually not. They control different layers and compose cleanly. Docker isolates the MCP server process itself, with containers, capped CPU and memory, no host filesystem access by default, and signed catalog images; KnoxCall governs the calls reaching that server, with audience-confined tokens, tool allowlists that deny when empty, PII detection on tool arguments, and per-call attribution. If your worry is what a third-party server binary does on a developer machine, Docker is the right tool and we do not offer that.
Not as a shipped feature, on the evidence we could find. Its README enumerates seven features, Container-based Servers, Server Management, Secrets Management, OAuth Integration, Server Catalog, Dynamic Discovery and Monitoring, and PII or DLP inspection is not among them, nor does the Gateway documentation page mention it. Its block-secrets flag is credential-pattern matching rather than PII classification. Custom inspection is possible through its interceptor extension point, but we found no bundled PII plugin. Verified against docs.docker.com and github.com/docker/mcp-gateway on 25 August 2026.
Three things, each of which is a refusal you can reproduce. A token is bound to one MCP server under RFC 8707, so presenting it at a different server is a 401 and a token carrying no resource binding is also a 401 rather than being treated as unrestricted. An empty tool allowlist advertises nothing rather than everything, and a caller token can narrow that set but never widen it. And the same gateway governs your model traffic, so budgets, model policy and mid-stream PII redaction are one system and one bill rather than two.
Docker MCP Gateway is open source under MIT, but its organisation-level governance, approving servers, requiring approval for tool calls, and MCP policy audit logs, is Docker AI Governance, which its documentation states is available on a separate paid subscription, and the Catalog page notes the gateway integration is invite-only. KnoxCall's tool governance is in the product from the free tier. Verified on 25 August 2026.
Yes, and many teams should. Docker isolates the server process while KnoxCall governs the calls reaching it. Nothing in either design conflicts with the other, and a comparison page that told you otherwise would be selling rather than comparing.
Audience-confined tokens, allowlists that deny by default, inspection on the arguments — free to start.