API Gateway

4 open source tools compared. Sorted by stars — scroll down for our analysis.

Tool	Stars	Velocity	Language	License	Score
Kong Cloud-native API gateway	43.1k	+44/wk	Lua	Apache License 2.0	79
APISIX Cloud-native API and AI gateway	16.4k	+38/wk	Lua	Apache License 2.0	79
tyk	10.7k	+8/wk	Go	MPL 2.0	80
emissary	4.5k	—	Python	Apache-2.0	69

Our Analysis

Kong43.1k★

Kong is an API gateway that sits between your clients and services, handling authentication, rate limiting, logging, transformations, and load balancing. It sits between your clients and your services and manages traffic, security, and observability in one place. Kong Gateway (OSS) is free and covers the fundamentals: request routing, load balancing, health checks, and a plugin system with 30+ free plugins (rate limiting, key auth, JWT, CORS, request transformation, logging). It runs on OpenResty/Nginx, so it's fast. Configuration via a REST Admin API or declarative YAML. Kong Enterprise (Kong Konnect) adds the management UI, developer portal, Vitals analytics, RBAC, OpenID Connect, and a managed control plane. Pricing is custom but typically starts around $15K+/year. Solo: probably overkill. Use a reverse proxy. Small teams: Kong OSS works well for <20 services. Growing teams: evaluate Konnect when you need the dashboard. Large orgs: Kong is industry standard at this tier. The catch: Kong without the management UI means configuring everything via API calls or YAML. That's fine for a few services but becomes painful at scale. The plugin ecosystem is powerful but writing custom plugins requires Lua knowledge (or Go/Python with newer PDK). If you want a simpler API gateway, APISIX or even Caddy with plugins might be less overhead.

APISIX16.4k★

APISIX is an API gateway built on Nginx and Lua that sits in front of your microservices, handling routing, authentication, rate limiting, and payload transformation fast enough for serious traffic. It routes API calls to the right backend service and applies policies (auth, rate limits, logging) without changing your application code. Fully free under Apache 2.0. APISIX is an Apache Software Foundation project with no commercial entity gating features. You get the full gateway: dynamic routing, load balancing, 80+ plugins (auth, observability, traffic control), gRPC support, and a dashboard. Plugins are hot-reloadable, no restarts required. The catch: the Lua/OpenResty foundation is niche. If your team doesn't know Lua, writing custom plugins is a steep learning curve. Envoy and Traefik have larger communities and more ecosystem integrations. And while APISIX is fast, the operational complexity of running an API gateway at scale (high availability, configuration management, monitoring) is real regardless of which tool you pick.

tyk10.7k★

Tyk is an API gateway that sits in front of your services and handles authentication, rate limiting, analytics, and versioning. Consider it a bouncer for your API: checks credentials, enforces quotas, logs everything. Go-based. Tyk's open source gateway handles the core job: proxying requests, applying rate limits, key authentication, and basic analytics. It's Docker-friendly and runs as a single binary. The open source gateway is free under a modified license (check the terms; it's not a standard permissive license). The paid tiers add a management dashboard, developer portal, multi-data-center support, and enterprise SSO. Tyk Cloud starts around $500/mo. Self-hosted pro licenses are custom-quoted. Solo or small teams: the free gateway handles basic API management fine. You configure it via API calls or config files, no GUI. Medium teams: you'll probably want the dashboard once you're managing 10+ APIs. Large orgs: the enterprise features (RBAC, federation, portal) justify the cost. The catch: the free tier is deliberately limited to push you toward paid. No dashboard, no developer portal, no visual API designer. The licensing is also murky, not Apache or MIT, so check compliance before deploying commercially. Kong is the more common open source choice with a clearer license story.

emissary4.5k★

Emissary-ingress is an API gateway built on Envoy Proxy. It handles routing, TLS termination, rate limiting, authentication, and load balancing for traffic entering your Kubernetes cluster. It's the front door to your cluster that decides which request goes where. Fully free under Apache 2.0. CNCF incubating project. You get the full gateway: path-based routing, header-based routing, gRPC support, WebSocket support, automatic TLS with Let's Encrypt, rate limiting, and OAuth2 integration. Configured via Kubernetes CRDs (Custom Resource Definitions). The catch: Emissary's development has slowed significantly. Ambassador Labs (the company behind it) has shifted focus to Telepresence and their commercial products. The Kubernetes gateway API is becoming the standard, and newer ingress controllers (like Envoy Gateway, which is also Envoy-based) are more actively developed. If you're starting fresh, Envoy Gateway or Traefik are better bets. If you're already running Emissary, it works, but plan a migration timeline.