which is best api gateway for building claude agents?
our team has been developing Claude agents and building a SaaS backend. We are currently selecting a suitable API gateway. Spiky workloads mean our traffic is not a smooth, linear growth. Some days, our agents send massive requests to the API, followed immediately by dead periods. If we get tied to fixed subscription plans, we are simply burning money on idle compute resources.so a payg plan is a hard requirement for us.
This is our review after evaluating some popular options Openrouter: ideal for developers experimenting with multiple models who need a unified, flexible API for routing. Its flexibility allows you to route between different models, set fallbacks, and manage a unified budget, with highly adaptable payment options like crypto and bank transfers. Anthropic-compatible endpoint easily plugs into existing codebases.
However, while strong for multi-model routing, full compatibility for advanced, Claude-specific native features often depends on the underlying provider and is most reliable using first-party nodes. Zenmux: more lightweight and cost-focused. It did not add extra platform fees on top of token usage, which made costs easier to reason about for spiky workloads.
The fallback experience also felt solid in practice, but I would not describe it as a unique feature. It is more that Zenmux handled the basic gateway expectations well without adding too much configuration overhead. For our use case, it felt like a practical middle ground: less complex than a full control plane, but still good enough for routing, api/cost/usage tracking, and handling unstable upstreams.
Portkey: designed for production-heavy teams requiring high level observability, strict compliance, and advanced routing logic. It acts as a massive control plane, offering detailed logging, cost-saving caching, and great fallback to ensure smooth transitions if endpoints fail.
However, this heavyweight gateway introduces real configuration overhead and complexity to your codebase. If you only need a simple proxy, configuring their extensive tracking, load balancing, and caching rules can feel like overkill and might add an extra latency hop. For us, the decision mainly came down to workload pattern.
If you are experimenting with lots of models, openrouter is still the most flexible starting point. If your team has spiky agent traffic and wants simple routing and high obervability without extra platform fees or heavy setup, zenmux is the cleaner fit.
If you are running a larger production system and need deep observability, compliance, caching, and advanced routing logic, Portkey makes more sense Our main takeaway: the “best” API gateway depends less on feature lists and more on your traffic pattern, engineering bandwidth, and how much control you actually need
