How do their APIs compare?

These two projects serve very different purposes, so their "APIs" are apples-to-oranges — one is a Java library API for building clients, the other is an Electron/Vue desktop app with an internal HTTP control API. Here's the comparison:

netflix/ribbon: a client-side IPC/library API

Ribbon exposes Java APIs meant to be embedded in other applications that make remote calls. Key surface areas:

• HTTP request/response abstractions: HttpRequest models an outgoing call with a Verb enum (GET/PUT/POST/DELETE/OPTIONS/HEAD), headers (CaseInsensitiveMultiMap), query params, and an entity body, built via a Builder pattern [ribbon-httpclient/src/main/java/com/netflix/client/http/HttpRequest.java:L37-L76]. HttpResponse is the corresponding response abstraction [ribbon-httpclient/src/main/java/com/netflix/client/http/HttpResponse.java:L1-L34].
• Client execution: RestClient.execute(HttpRequest, IClientConfig) is the main entry point for firing a request, optionally overriding client config per-call [ribbon-httpclient/src/main/java/com/netflix/niws/client/http/RestClient.java:L462-L470].
• Configuration: IClientConfig is the central configuration interface used across load balancers and clients [ribbon-core/src/main/java/com/netflix/client/config/IClientConfig.java:L1-L30], and IClientConfigAware is a marker interface for components that need config injected [ribbon-core/src/main/java/com/netflix/client/IClientConfigAware.java:L17-L30].
• Load balancing / fault tolerance: exposed via composable predicates like CompositePredicate, which ANDs predicates together with fallback behavior when too few servers pass filtering [ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/CompositePredicate.java:L1-L39].

This is a programmatic, in-process API — consumers add ribbon as a Maven dependency and call these Java classes directly. Per the README, it also supports async/reactive APIs (via Observables) and multiple protocols (HTTP/TCP/UDP) through ribbon-transport.

proxyee-down-org/proxyee-down: an internal HTTP/REST-ish control API

Proxyee-down is a desktop download manager (Electron-style, with a Vue frontend and Java/Netty backend). Its "API" is a local HTTP server the frontend talks to, not a library for embedding:

• Frontend calls hit endpoints like /tasks (POST) and /util/resolve (PUT) and /config (PUT), with numeric error codes (4000–4007) mapped to user-facing messages in the i18n file [front/src/i18n/en-US.js:L152-L172].
• A native bridge module (front/src/common/native.js) wraps axios calls to a local native endpoint, e.g. getUpdateProgress() hitting /native/getUpdateProgress [front/src/common/native.js:L238-L245].
• On the backend, DefaultController.handle(Channel, FullHttpRequest) serves static resources over HTTP (mapping file extensions to MIME types) rather than exposing a typed request/response object model like Ribbon's HttpRequest/HttpResponse [main/src/main/java/org/pdown/gui/http/controller/DefaultController.java:L19-L45].
• There's also an MITM interception layer (SniffIntercept) that inspects/filters HTTP traffic by content type for its download-capture feature [main/src/main/java/org/pdown/gui/extension/mitm/intercept/SniffIntercept.java:L158-L192], which is unrelated to any public "API" surface — it's internal proxy plumbing.

Key differences

1. Audience: Ribbon's API is for developers embedding a library in JVM services; proxyee-down's API is a private frontend↔backend contract for its own Electron/Vue app, not intended for third-party consumption.
2. Abstraction level: Ribbon models requests/responses as typed Java objects with builders and enums [ribbon-httpclient/.../HttpRequest.java:L37-L76]; proxyee-down mostly deals in raw Netty `FullHtt