Here are well‑known open‑source alternatives to Apigee and MuleSoft for API gateway / management functionality, grouped and summarized so you can compare quickly.

Core API gateways / management platforms

• Kong (Kong Gateway, OSS edition)

  • Lua / plugin architecture, high performance, rich plugin ecosystem (auth, rate limiting, logging).
  • Can run standalone or on Kubernetes. Enterprise features are paid.
  • Good if you need a mature, extensible gateway with an active community.

• Apache APISIX

  • High performance (written in Lua/OpenResty), dynamic routing, plugin system, good for realtime config changes.
  • Strong Kubernetes integration and growing cloud-native ecosystem.

• Tyk (Tyk OSS / Community)

  • Lightweight gateway + built‑in dashboard in paid edition; community edition provides core gateway, policy and plugin support.
  • Good if you want a simpler setup with out-of-the-box throttle/auth policies.

• Gravitee.io (API Management & Gateway)

  • Full API management feature set (gateway, portal, analytics) in OSS edition; modular and developer-friendly.
  • Good choice when you want API lifecycle features without commercial vendor lock-in.

• WSO2 API Manager

  • Full lifecycle API management (design, publish, governance, analytics) with strong enterprise capabilities.
  • Heavier but feature-complete for organizations replacing full MuleSoft/Apigee stacks.

• KrakenD

  • Focuses on high-performance API aggregation and transformation (API gateway for composing backends).
  • Great for building façade/aggregation gateways and reducing backend calls.

Kubernetes / cloud-native ingress & API gateways

• Ambassador / Emissary-ingress

  • Kubernetes-native gateway built on Envoy; focuses on developer workflow and integrations.
  • Good when you run primarily on Kubernetes and want Envoy-based routing with API features.

• Istio (and other service meshes: Linkerd, Consul)

  • Primarily a service mesh for mTLS, observability, traffic control; includes ingress/gateway capabilities.
  • Use if you need mesh features (service-to-service security/observability) as well as gateway functions.

• Traefik

  • Dynamic cloud-native reverse proxy / ingress gateway with middlewares for routing, auth, rate limiting.
  • Simple to operate; ideal for smaller teams or simple gateway needs on Kubernetes.

Frameworks / language-specific gateways

• Spring Cloud Gateway

  • Java / Spring ecosystem; programmable routes and filters.
  • Best if your stack is Java/Spring Boot and you want tight integration.

• Ocelot

  • Lightweight .NET API gateway for microservices written in .NET Core.
  • Good for .NET environments with simple routing & aggregation needs.

Other older / niche options

• Netflix Zuul (legacy; Zuul 1 is mature but older; Zuul 2 is non‑OSS in parts)
  • Historically popular but less common today compared with Envoy-based solutions.

How to choose (short checklist)

• Feature needs: full API lifecycle (developer portal, analytics, monetization) → Gravitee, WSO2, Kong Enterprise / paid tiers.
• Performance & dynamic routing: APISIX, Kong, Envoy-based (Ambassador).
• Kubernetes-native: Ambassador, Istio, APISIX, Traefik.
• Aggregation / transformation: KrakenD, Kong plugins.
• Language/stack fit: Spring Cloud Gateway (Java), Ocelot (.NET).
• Operational complexity vs simplicity: Traefik/Kong (simpler) vs WSO2/WSO2 (heavier, enterprise features).

If you want, I can:

• Recommend the top 2–3 for your specific environment (Kubernetes vs VMs, expected throughput, required lifecycle features), or
• Provide quick deployment examples (Kubernetes manifests or Docker-compose) for any of the above.