Best LLM API Gateway Comparison for 2025

If you're searching for the best LLM API gateway, you're probably trying to solve one of a few problems: you have multiple apps or team members sharing one model subscription, you need usage tracking and per-app API keys, or you want a stable HTTPS interface instead of juggling raw provider credentials. The "best" gateway depends entirely on which of these problems you actually have.

This comparison breaks down the three main categories of LLM API gateways — self-hosted proxies, generic multi-provider routers, and managed single-provider gateways — so you can pick based on what you need rather than what's trending. We'll focus on Claude-based workflows since that's where most of the confusion around "which gateway do I need" actually comes from.

What an LLM API Gateway Actually Does

Before comparing options, it's worth being precise about the job. A good LLM API gateway should give you:

• Application-level API keys — separate credentials per app or project, not one shared secret
• Usage visibility — tokens, requests, and cost broken down by key or team
• A stable HTTP interface — streaming, tool use, and message formatting handled consistently
• Access control — the ability to revoke one key without breaking everything else
• Team management — seats, roles, and billing that doesn't require spreadsheet gymnastics

Not every tool in this category does all five. Some are narrow (just a proxy), some are broad (full multi-provider routing with fallback logic). Matching the tool to the job matters more than picking the "most powerful" one.

Category 1: Self-Hosted Reverse Proxies

Tools like LiteLLM, Portkey (self-hosted mode), or a custom Express/FastAPI proxy fall here. You run the service yourself, usually in a container, and it forwards requests to the provider's API while adding logging, rate limiting, or key rotation.

Strengths:

• Full control over routing logic and data residency
• Free beyond your own infrastructure costs
• Good fit if you already have DevOps capacity and specific compliance requirements

Weaknesses:

• You own uptime, scaling, and security patching
• Dashboards (if any) are usually basic or require separate setup
• Team seat management and billing are not built in — you'd build that yourself
• Every provider API change is your problem to track and fix

This is the right choice if you have infrastructure engineers with spare capacity and specific requirements a managed service can't meet. For most product teams, it's a maintenance burden disguised as a cost saving.

Category 2: Generic Multi-Provider Routers

Services like OpenRouter or multi-provider SDKs aim to abstract away the differences between OpenAI, Anthropic, Google, and others behind one interface. The pitch is flexibility: swap providers without rewriting your integration.

Strengths:

• Useful if you genuinely need to compare or fall back across multiple model providers
• Often pay-as-you-go with no separate subscription

Weaknesses:

• Abstraction layers smooth over provider-specific features, which means you sometimes lose access to things like fine-grained tool use or provider-specific streaming behavior
• You're usually billed by the router in addition to provider costs, or through a markup
• If you've already committed to Claude specifically, the multi-provider abstraction adds complexity you don't need

This category makes sense if provider flexibility is a real business requirement — for example, if you're building a product where customers choose their own model. If you've already standardized on Claude, it's solving a problem you don't have.

Category 3: Managed Single-Provider Gateways

This is where tools like SubToAPI sit. Instead of routing across providers, the goal is to take the Claude access you already pay for and turn it into a clean, multi-tenant HTTPS API — with per-app keys, streaming, tool use, and usage metadata available from day one.

Strengths:

• No infrastructure to run or patch
• Application API keys (sub_live_...) issued per app or client in the dashboard, each revocable independently
• Streaming and tool use work the same as the native Claude API because there's no abstraction layer reinterpreting requests
• Usage metadata per key, useful for billing clients or tracking internal cost centers
• Team seats with role-based access, so you're not sharing one login across a dev team

Weaknesses:

• Single-provider by design — if you need to route across multiple LLM vendors, this isn't the tool
• Adds a small monthly cost on top of your Claude access (Solo at €9, Team at €19/seat, Scale at €49/seat)

For teams that have standardized on Claude and need multiple apps or team members to use it safely — without sharing raw credentials or building their own key-management layer — this category gives the best return on setup time. You get the quickstart guide running in minutes rather than spending a sprint building a proxy.

How to Choose

A simple decision path:

1. Do you need multiple LLM providers behind one interface? If yes, look at generic routers.
2. Do you have DevOps capacity and specific compliance needs that require full control? If yes, self-host a proxy.
3. Are you standardized on Claude and need per-app keys, usage tracking, and team seats without maintaining infrastructure? A managed gateway like SubToAPI is the fastest path. Check pricing and start with the free trial at signup.

In practice, most product teams land in option 3 — they picked Claude for a reason, and the gateway problem is really a key-management and billing problem, not a routing problem.

Example: calling through a managed gateway

curl https://api.subtoapi.app/v1/messages \
  -H "Authorization: Bearer $SUBTOAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Summarize this changelog in 3 bullets."}
    ]
  }'

Each app gets its own key, each key's usage shows up in the dashboard, and streaming or tool use work exactly as documented in the Messages API reference.

questions

Do I need a gateway if I'm only building one app? Probably not. A single app with one developer can call Claude directly. Gateways earn their keep once you have multiple apps, clients, or team members sharing access and need separate keys or usage tracking.

Is a multi-provider router better than a single-provider gateway? Only if you actually need multiple providers. If you've committed to Claude, a single-provider gateway avoids the abstraction overhead and gives you full access to provider-specific features like streaming and tool use.

Can I switch from a self-hosted proxy to a managed gateway later? Yes — since both sit in front of the same underlying Claude API, migrating usually means updating your base URL and API keys. Check the docs for the request format before switching.