Claude Gateway: Route Claude and Claude Code Through One Unified AI Gateway

TL;DR

• One Anthropic-compatible entry point covers both Anthropic Claude models and Claude Code, so failover, governance, caching, and observability are configured once rather than per client.
• Bifrost exposes a fully Anthropic-compatible /anthropic endpoint that existing Anthropic SDK code reaches with one base-URL change.
• Claude Code routes through Bifrost by setting ANTHROPIC_BASE_URL and ANTHROPIC_AUTH_TOKEN in settings.json, and no separate Anthropic account login is required.
• Virtual keys carry their own budgets, rate limits, and model-access policies, so application traffic and coding-agent traffic fall under the same controls.
• Bifrost routes across 25+ providers and 10,000+ models, and adds 11 microseconds of overhead per request at 5,000 requests per second in sustained benchmarks.

A Claude gateway is a single entry point that routes requests to Anthropic Claude models and to Claude Code (the terminal coding agent) through one Anthropic-compatible API, adding failover, governance, caching, and observability without changes to application or agent code. Bifrost, the open-source AI gateway built in Go by Maxim AI, provides this by exposing a fully Anthropic-compatible /anthropic endpoint that existing Claude SDK code and Claude Code point at with a single base-URL change. This post covers how Bifrost works as a Claude gateway: the drop-in Anthropic-compatible API, multi-provider routing with failover to and from Claude, governance over Claude usage, semantic caching, observability, and how to point Claude Code at Bifrost.

What Is a Claude Gateway

A Claude gateway is an intermediary service that sits between your application (or coding agent) and Anthropic's API, accepting Anthropic-shaped requests, routing them to Claude or another configured provider, and returning responses in the Anthropic response format the client expects. It centralizes credentials, usage tracking, cost controls, and audit logging in one place. The same pattern underlies every AI gateway for Claude Code, whether the client is an application or a terminal agent.

Anthropic's own documentation describes the same pattern: a gateway gives an organization one place to manage credentials, usage tracking, cost controls, and audit logging, with the provider key kept server-side while developers hold gateway credentials instead. Per Anthropic's Claude Code gateway documentation, any gateway that exposes a supported API format works with Claude Code. Bifrost implements exactly this contract and extends it with multi-provider routing, failover, and semantic caching.

Why Teams Route Claude Through a Gateway

Teams route Claude through a gateway to solve three problems the Anthropic API does not solve on its own: there is no automatic failover, no central place to enforce budgets and model-access policies across distributed API keys, and no single view of latency, cost, and errors. A gateway addresses all three at one hop:

• Provider outages and rate limits: Direct Anthropic API calls have no automatic failover. A 429 rate-limit response or a 5xx outage propagates straight to the application.
• Ungoverned usage and cost: Individual API keys distributed to developers and services make it difficult to enforce per-team budgets, rate limits, or model access policies.
• No unified observability: Requests to Claude from applications, services, and coding agents are logged separately, if at all, with no single view of latency, cost, or errors.

Bifrost consolidates these concerns. It routes Anthropic Claude traffic through one endpoint while adding retries and fallbacks, per-key budgets and access policies, and built-in request logging. For enterprises running Claude at scale, this consolidation replaces per-key remediation with centralized control, which is the same shift covered in Claude Code gateway routing, governance, and cost control.

How Bifrost Works as a Claude Gateway

Bifrost exposes a fully Anthropic-compatible endpoint at /anthropic that accepts requests in Anthropic's Messages API format and returns responses in the same shape. This endpoint is the mechanism behind routing Claude through Bifrost: existing Anthropic SDK code keeps working, and the only change is the base URL.

The Bifrost drop-in replacement for the Anthropic SDK requires one line to change:

import anthropic

# Point the Anthropic SDK at Bifrost
client = anthropic.Anthropic(
    base_url="http://localhost:8080/anthropic",   # Only change needed
    api_key="<YOUR-BIFROST-VIRTUAL-KEY>"          # Provider keys stay server-side
)

response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1000,
    messages=[{"role": "user", "content": "Hello!"}]
)

Bifrost handles the request transformation, response normalization, and error mapping between Anthropic's Messages API and its internal pipeline. Because the Anthropic SDK integration preserves the existing SDK architecture, applications gain governance, load balancing, caching, and multi-provider access without a rewrite.

Does Bifrost support Anthropic beta headers?

Yes. Bifrost automatically detects and injects the Anthropic beta headers a request requires, and validates them per provider so unsupported headers do not reach the upstream API. Headers such as prompt caching, interleaved thinking, and context management are auto-injected based on request features, and the per-provider beta header support matrix can be overridden where a deployment needs different defaults. Unrecognized beta headers can be added to an allowlist for full compatibility.

Multi-Provider Routing and Failover To and From Claude

Bifrost, the AI gateway for enterprise Claude workloads, routes requests across 25+ providers and 10,000+ models through the same Anthropic-compatible interface. Using the Anthropic SDK format, a client can address Claude by default and other providers by prefixing the model name:

# Claude (default)
client.messages.create(model="claude-sonnet-4-20250514", ...)

# OpenAI via the same Anthropic SDK format
client.messages.create(model="openai/gpt-4o-mini", ...)

# Google Vertex via the same Anthropic SDK format
client.messages.create(model="vertex/gemini-pro", ...)

This unified access is what makes failover possible. Bifrost provides two complementary resilience layers:

• Retries: When a provider returns a transient 5xx error or a per-key failure (429, 401, 402, 403), Bifrost retries against the same provider, rotating API keys from the pool and applying exponential backoff with jitter where appropriate.
• Fallbacks: When the primary provider fails after exhausting retries, Bifrost moves to the next provider in the fallback chain, and each fallback provider receives its own full retry budget.

How Bifrost classifies a failure decides what happens next:

Teams can configure Claude as the primary model with a secondary provider as fallback, or route to Claude as the fallback when a primary model becomes unavailable. Load balancing across multiple Anthropic API keys distributes traffic to avoid single-key rate limits. Bifrost, an open-source AI gateway built in Go, applies this routing with 11 microseconds of overhead per request at 5,000 requests per second in sustained benchmarks.

Governance Over Claude Usage

Governance in Bifrost is built on virtual keys, the primary governance entity. A virtual key carries its own access permissions, budgets, and rate limits, and clients authenticate to it using standard headers, including the Anthropic-style x-api-key header that Claude clients already send.

Virtual keys give teams centralized control over Claude usage:

• Access control: Restrict which providers and models a virtual key can call, so a key can be scoped to specific Claude models only.
• Budgets: Attach independent dollar budgets with reset periods ranging from minutes to a year (1m, 5m, 1h, 1d, 1w, 1M, 1Y), checked alongside team and customer budgets.
• Rate limits: Apply token-based and request-based throttling per virtual key.
• Key restrictions: Limit a virtual key to specific provider API keys.

Because governance is enforced at the gateway rather than distributed across raw Anthropic keys, an organization can issue a per-developer or per-service virtual key, set its budget and rate limit, and revoke it instantly. The governance resource page covers how hierarchical cost control works across virtual key, team, and customer levels.

For regulated environments, Bifrost Enterprise records audit logs of administrative activity as signed events, so operators can review who changed a provider, virtual key, or policy, when the change happened, and which resource it affected. Those events can be filtered and exported to a SIEM or log-forwarding pipeline. Bifrost can also be deployed in-VPC for teams that require private cloud isolation.

Semantic Caching for Claude Requests

Bifrost, the AI gateway that fronts Claude, can cache Claude responses and replay them for repeated or semantically similar requests through semantic caching. It offers two complementary lookup paths:

• Direct (hash) matching: Deterministic exact-match replay. The request is normalized and hashed, and an identical request is served instantly with no embeddings required.
• Semantic (similarity) matching: Embedding-based lookup that serves a cached answer when a new request is close enough to a previous one, even when the wording differs.

Both modes reduce cost by skipping paid Claude calls for repeated prompts. The latency gain differs by path: a direct hit returns in sub-millisecond time against a local vector store, while a semantic lookup must first embed the request, costing an embedding round-trip before the answer is served. Streamed responses are cached and replayed chunk by chunk, so caching works for streaming Claude output as well.

Pointing Claude Code at Bifrost

Claude Code, Anthropic's terminal coding agent, reads the ANTHROPIC_BASE_URL environment variable at startup and sends every API request there instead of to Anthropic. Setting that variable to Bifrost turns Bifrost into the Claude gateway for the coding agent, and the same failover, governance, and observability apply to agent traffic. Per Anthropic's Claude Code gateway documentation, the gateway must answer in the Anthropic format, which Bifrost does through its /anthropic endpoint.

To route Claude Code through Bifrost, set the base URL to the Bifrost Anthropic endpoint and authenticate with a Bifrost virtual key. Add the following to ~/.claude/settings.json:

"env": {
  "ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
  "ANTHROPIC_AUTH_TOKEN": "your-virtual-key"
}

Claude Code sends the ANTHROPIC_AUTH_TOKEN value in the Authorization: Bearer header, which Bifrost recognizes as the virtual key for routing and authentication. With this method, no separate Anthropic account login is required because Bifrost handles authentication through the virtual key.

The two variables that can carry the virtual key differ in one respect:

Where the Authorization header is already claimed by another tool in the chain, such as an MCP connection running alongside the gateway, Bifrost also accepts the virtual key in X-Api-Key or x-bf-vk. Per-developer cost tracking for Claude Code builds on the same key.

Can Claude Code use models other than Claude through Bifrost?

Yes. Because Bifrost routes across every configured provider, a routing rule can map the model names Claude Code sends to any provider and model in Bifrost. Anthropic does not support or endorse routing Claude Code to non-Claude models, so teams that do this operate it themselves, but the mechanism is available through Bifrost routing rules and dynamic aliasing. The operational trade-offs are covered in running non-Anthropic models in Claude Code and in the guide to using Claude Code with any LLM.

How does Bifrost govern Claude Code usage?

Claude Code traffic authenticates against a Bifrost virtual key, so the same budgets, rate limits, and model-access policies that govern application traffic also govern the coding agent. A per-developer virtual key attributes agent usage to that developer and can be revoked on offboarding, matching the rollout pattern Anthropic recommends for gateway credentials. This is the basis of securing agent access with an AI gateway.

Observability for Claude Traffic

Every request routed through Bifrost is logged and can be monitored in real time. The built-in logging dashboard captures Claude application traffic and Claude Code agent traffic in one place, with filtering by provider, model, or conversation content.

For production monitoring, Bifrost integrates with standard observability stacks:

• Prometheus: Native metrics through scraping and Push Gateway.
• OpenTelemetry (OTLP): Distributed tracing compatible with Grafana, New Relic, and Honeycomb.
• Datadog: A native connector for APM traces, LLM Observability, and metrics.

Bifrost publishes its observability configuration so teams can route Claude traffic metrics into an existing monitoring pipeline. This unified view is what allows a platform team to track Claude cost, latency, and error rates across every surface that touches the model.

Frequently Asked Questions

What is the difference between a Claude gateway and the Anthropic API?

The Anthropic API is the origin service that serves Claude models. A Claude gateway sits in front of it, accepts the same request format, and adds routing, failover, governance, caching, and logging before forwarding the call. Clients keep speaking the Anthropic Messages API, so the difference is operational rather than functional: one base URL changes, and control moves to the gateway.

Does routing Claude through a gateway change the response format?

No. Bifrost returns responses in the Anthropic response shape the client expects, because the /anthropic endpoint performs protocol adaptation in both directions. Streaming works the same way, with chunks passed through in Anthropic's event format. Code that parses Anthropic responses continues to work unchanged.

Can a Claude gateway reduce Anthropic API costs?

Yes, through three mechanisms. Exact-match and similarity caching replays answers for repeated or similar prompts instead of paying for another Claude call. Budgets and rate limits on virtual keys cap spend per developer, team, or customer before it is incurred. Routing rules can send lower-value requests to cheaper models while high-value traffic stays on Claude.

Can application traffic and Claude Code traffic share one gateway?

Yes, and that is the usual deployment. Both speak the Anthropic format, so both point at the same /anthropic endpoint and authenticate with virtual keys. The result is one set of budgets, rate limits, and model-access policies, and one request log covering application calls and coding-agent calls together, which is what makes cost attribution across the two possible.

Getting Started with Bifrost as a Claude Gateway

A Claude gateway consolidates routing, failover, governance, caching, and observability for Anthropic Claude models and Claude Code behind one Anthropic-compatible API. Bifrost, the open-source AI gateway built for enterprise AI workloads, implements this through its drop-in /anthropic endpoint, so pointing an application or Claude Code at Bifrost requires only a base-URL change. Teams evaluating gateways can review the LLM Gateway Buyer's Guide and the Bifrost governance resources for capability details, and the complete guide to choosing a gateway for Claude Code for a wider comparison of the options.

To see how Bifrost can serve as the Claude gateway for your applications and coding agents, book a demo with the Bifrost team.