RelayPlane vs LiteLLM vs OpenRouter: an honest comparison for cost caps and routing

Matt — Thu, 24 Sep 2026 19:33:54 +0000

If you want a hard daily spend cap and a per-request cost ledger on one machine with no database server to run, RelayPlane is the smallest install of the three (@relayplane/proxy on npm, free, MIT). If you want 100+ providers behind one gateway for a team, LiteLLM is the better tool. If you want a hosted API you don't run yourself, OpenRouter is the better tool. All three are real, none of them is a straight replacement for the other two, and this piece is an honest breakdown of where each one actually wins.

I built RelayPlane, so I'm biased. Every RelayPlane line below matches its code or docs, and the LiteLLM and OpenRouter lines come from their own docs, linked under the table, so you can check them yourself.

What each one is, in one line

RelayPlane: a local proxy that meters every request on the machine it runs on, enforces a hard spend cap before the request leaves, and has a kill switch. No Docker, no Python, runs on localhost:4100.
LiteLLM: an open source AI gateway for a team, deployed as a service with virtual keys, per-tenant budgets, and 100+ providers behind one OpenAI-format API.
OpenRouter: a hosted API that gives you one key and one endpoint for 500+ models across many providers, no infrastructure to run, billed through their platform.

The comparison

	RelayPlane	LiteLLM	OpenRouter
What it is	Local proxy for one machine	Self-hosted gateway for a team	Hosted model marketplace
Install	`npm install -g @relayplane/proxy`	`pip install` or `uv`, run the proxy	No install, API key only
Runs locally	Yes	Yes (self-hosted)	No, cloud only
Native providers	6 (Anthropic, OpenAI, Gemini, xAI, Ollama, and OpenRouter passthrough)	100+	500+ (it IS the aggregator)
Per-request cost ledger on your machine	Yes, a local SQLite file, nothing to deploy	Spend logs live in the proxy's database	Dashboard on their cloud
Hard daily spend cap enforced before the request leaves	Yes (`relayplane cap set --day 50`, returns 429)	Budgets per virtual key, team, user	Per-key credit limits, enforced in their cloud
Kill switch	Yes, one command, survives a restart	Block a virtual key via the admin API	Disable the key in their dashboard
Routing by task complexity	Yes, one config field, hot reloads	Router strategies you configure per deployment	No, you pick the model per call
Virtual keys / multi-tenant budgets	No	Yes, this is its core job	Per-key limits, cloud side
Self-hosted	Yes	Yes	No
Where your data lives	Your machine only	Wherever you deploy it	Their servers
License / model	MIT, everything free	MIT + enterprise license and hosted option	Proprietary, 5.5% fee on credit purchases

The LiteLLM column comes from github.com/BerriAI/litellm and docs.litellm.ai, the OpenRouter column from openrouter.ai/docs, and the RelayPlane column from github.com/RelayPlane/proxy and relayplane.com/docs.

Where LiteLLM wins outright

Provider breadth and the multi-tenant model. If you're running a platform team with multiple apps and want virtual keys, per-team budgets, load balancing across many deployments, and an admin dashboard for the whole org, that's what LiteLLM is built for. RelayPlane has none of that, it tracks one machine, not a tenant hierarchy.

Where OpenRouter wins outright

Zero infrastructure. You get an API key and you're calling 500+ models in one format, with nothing to run or maintain. The tradeoff is you don't get a local, offline-readable cost ledger or a hard cap enforced before the request leaves your machine, you're working from their dashboard and their usage API.

Where RelayPlane's narrow wedge is

Three things. I use all of them daily on a pipeline that routes real production traffic.

A per-request ledger with no database server to run. Every request through localhost:4100 gets priced and written to a local SQLite file with model, tokens, cost, agent, and session. relayplane kills --last 7d shows every blocked request with the agent and session that caused it.
A hard cap the proxy enforces, not a report you read after the bill arrives. relayplane cap set --day 50 returns 429 budget_exceeded on the request that would cross $50. Choose block, downgrade to a cheaper model, or warn.
A kill switch that survives a restart. relayplane kill returns 503 kill_switch_active on every routed request until relayplane resume.

You don't need a database server or an account for any of it. It's a single npm install.

The honest answer to "which one should I use"

Pick RelayPlane if you're solo or on one machine and want to see and cap what you're spending without standing up infrastructure.
Pick LiteLLM if you run a platform team with several apps and users, and budgets that need enforcing per tenant.
Pick OpenRouter if you don't want to run anything and just need one key for a lot of models.
If you want OpenRouter's model catalog and a hard local cap, point RelayPlane at OpenRouter as its upstream. RelayPlane keeps the ledger and the kill switch, and OpenRouter supplies the models.

Try it

npm install -g @relayplane/proxy
relayplane init
relayplane start
export ANTHROPIC_BASE_URL=http://localhost:4100

That's the whole setup. Source is at github.com/RelayPlane/proxy, MIT licensed, free, no paid tier.

DEV Community: Matt