Comparison with Other HTTP Client Libraries

HttpAgent, Refit and RestSharp are all popular HTTP client solutions in the .NET ecosystem, each with a different focus: Refit champions "interface as API" declarative programming, RestSharp is the classic, battle-tested fluent client, and HttpAgent is the full-featured option — beyond everyday requests it ships SSE, WebSocket, long polling, stress testing and the Profiler traffic-analysis engine out of the box, with zero third-party dependencies.

Typical usage side by side

The same "fetch a list of users" in each library:

HttpAgent: builder or predicate style — your choice

// Option 1: fluent buildervar users = await httpRemoteService.SendAsAsync<List<User>>(    HttpRequestBuilder.Get("https://api.example.com/users"));// Option 2: request predicate (syntactic sugar)var users = await httpRemoteService.GetAsAsync<List<User>>("https://api.example.com/users");

Refit: interface as API

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public interface IUsersApi{    [Get("/users")]    Task<List<User>> GetUsersAsync();}var api = RestService.For<IUsersApi>("https://api.example.com");var users = await api.GetUsersAsync();

RestSharp: classic RestClient + RestRequest

var client = new RestClient("https://api.example.com");var request = new RestRequest("/users");var users = await client.GetAsync<List<User>>(request);

Notice that Refit requires an interface contract up front, while RestSharp and HttpAgent are write-as-you-go fluent styles — and HttpAgent supports both.

Common REST capabilities

Capability	`HttpAgent`	`Refit`	`RestSharp`
Standard verbs (`GET`/`POST`/`PUT`/`DELETE`, …)	✅ 9 verbs	✅ interface attributes	✅ `RestRequest`
Fluent builder	✅ `HttpRequestBuilder`	❌ (interface-based, no builder)	✅ `RestClient` + `RestRequest`
Declarative interface (proxy)	✅ declarative proxy	✅ (core design)	❌
Query params / headers / body	✅	✅	✅
`JSON`/`XML` serialization	✅ built-in content processors	✅ `System.Text.Json` (replaceable)	✅ pluggable serializers
Multipart form upload	✅ `MultipartFile.CreateFromPath`	✅ `StreamPart` etc.	✅ `.AddFile(...)`
File upload / download (with progress)	✅ built-in progress output	✅ streaming responses	✅ `DownloadDataAsync` etc.
Authentication	✅ `Bearer`/`Basic`/`Digest`/`Access Token` auto-management + `JWT` utilities	✅ `[Authorize]` custom handlers	✅ `OAuth1/OAuth2/JWT/NTLM` authenticators
Retry policy	✅ built-in retry + quota policy	❌ (bring your own `Polly`)	✅ official `Polly` integration
Timeout	✅ built-in	✅ via `HttpClientHandler`	✅ `client.Timeout`
Redirect handling	✅ built-in (configurable delegate)	✅ client follows by default	✅ configurable
`HTTP` proxy	✅ built-in	✅ via `HttpMessageHandler`	✅ via `HttpMessageHandler`
Automatic decompression (`gzip`/`deflate`/`brotli`/`zstd`)	✅ built-in	✅ via `HttpMessageHandler`	✅ via `HttpMessageHandler`
`Cookie` management	✅ built-in	❌ (handle it yourself)	✅ built-in
Exception handling	✅ unified exceptions + suppression	✅ `ApiException`	✅ built-in exceptions
Cancellation (`CancellationToken`)	✅	✅	✅

Capabilities unique to `HttpAgent` (not built into the other two)

Capability	`HttpAgent`	`Refit`	`RestSharp`
`SSE` (`Server-Sent Events`, incl. `IAsyncEnumerable<T>`)	✅ built-in	❌	❌
`WebSocket` duplex communication	✅ built-in	❌	❌
Polling (standard + long polling, configurable interval)	✅ built-in	❌	❌
`Profiler` traffic-analysis engine (capture & visualize requests/responses)	✅ industrial-grade, built-in	❌	❌
Stress / performance / simulation testing (configurable concurrency & iterations, reports)	✅ built-in	❌	❌
Request assertions (pre-send / post-response checks)	✅ `Asserts(...)`	❌	❌
Content processor / converter dual pipeline (pluggable)	✅ built-in	❌	❌
`MessagePack` serialization	✅ built-in	❌	❌
`WebService` / `SOAP` support (incl. `SOAPAction`)	✅ built-in	❌	❌
`OData` client (`$filter`/`$select`/`$expand`)	✅ built-in	❌	❌
Request proxying & forwarding (microservice integration)	✅ built-in	❌	❌
Request log auditing (custom `Logger`)	✅ built-in	❌	❌
Website "Workshop" visual code generator	✅ (one-click builder/verb/`cURL`/declarative/`JSON` code)	❌	❌
Website "HttpAgent Assistant" AI Q&A	✅ (grounded in the official docs; select any text on the page to ask the AI; key stays local)	❌	❌
`cURL` command import	✅ built-in (visual generator on the website Workshop)	❌	❌
`JSON` config import	✅ built-in (`HttpRequestBuilder.FromJson()`)	❌	❌
`ETag` cache / request quota	✅ built-in	❌	❌
`HttpContext` forwarding	✅ built-in	❌	❌
`MCP` message content	✅ built-in	❌	❌
`Mock` simulation testing	✅ built-in	❌	❌
Third-party dependencies	zero	`System.Text.Json` etc.	serializers etc.

Which one should you pick?

A few REST endpoints and an interface-contract style → Refit is a great fit;
Legacy projects, ecosystem maturity and a huge body of community knowledge → RestSharp is a safe bet;
The full "request + debug + stress test + realtime" toolbox without assembling multiple libraries → HttpAgent is the ideal choice: zero dependencies, built-in Profiler, and SSE/WebSocket/long polling/stress testing/declarative requests all ready to use — plus the website's Workshop (visual code generator) and the "HttpAgent Assistant" AI Q&A to lower the learning and debugging curve.