RestSharp: A .NET REST Client That Wraps HttpClient

What RestSharp Solves for .NET HTTP Calls

The README describes RestSharp as a lightweight HTTP API client library and, more precisely, a wrapper around HttpClient rather than a full-fledged client on its own. That framing matters because it sets expectations. You are not replacing the .NET HTTP stack; you are putting a convenience layer on it.

The problem it addresses is repetition. Raw HttpClient calls require you to assemble query strings, set headers, pick a serializer, and handle authentication by hand. RestSharp adds default parameters of any kind, not just headers, and lets you attach a parameter of any kind to a request: query, URL segment, header, cookie, or body. It also ships built-in serialization and deserialization of JSON, XML, and CSV, plus the ability to add custom serializers.

Who it is for: C# developers writing client code against a REST API who want less boilerplate per endpoint. It is less obviously aimed at teams that need a supported commercial SDK or that already have a thin internal wrapper they are happy with.

How RestSharp Wraps HttpClient

The architecture described in the README is a wrapper. RestSharp 107 was a major release that removed a lot of legacy code and moved the library to HttpClient. The compatibility note lists what was deprecated in that release: SimpleJson in favour of System.Text.Json.JsonSerializer, IRestRequest and IRestResponse in favour of implementing classes, everything Http and IHttp because those are just wrappers, and client configuration moved to RestClientOptions to make the client thread-safe. The IRestClient interface surface was substantially reduced.

The practical consequence is that most client options and some request options now live in RestClientOptions, not on the client itself. That is a deliberate design choice: concentrating configuration in an options object is what makes the client thread-safe, which in turn makes it reasonable to share one client across concurrent calls. If you are porting code written before 107, this is the part that will hurt, because the old configuration points are gone.

Serialization is pluggable through separate packages. The core RestSharp package includes the System.Text.Json serializer and a basic XML serializer. RestSharp.Serializers.NewtonsoftJson swaps in Newtonsoft.Json, RestSharp.Serializers.Xml provides the custom RestSharp XML serializer, and RestSharp.Serializers.CsvHelper uses CsvHelper for CSV. That split means the serializer choice is explicit in your dependency list rather than hidden.

Getting the RestSharp Package and the Documented API Surface

The README does not include an install command or a code sample. It names the packages in a table, and that table is the only concrete guidance available here. The core library is the RestSharp package, described as including the System.Text.Json serializer and a basic XML serializer. Three companion packages change the serializer: RestSharp.Serializers.NewtonsoftJson for Newtonsoft.Json, RestSharp.Serializers.Xml for the custom RestSharp XML serializer, and RestSharp.Serializers.CsvHelper for CsvHelper.

Because the README gives no commands, this article will not invent any. What it does give is the API vocabulary you will meet once the package is referenced. RestClientOptions is where client configuration now lives, and the README ties that move to making the client thread-safe. Requests accept parameters by kind: query, URL segment, header, cookie, or body. Bodies can be JSON, XML, URL-encoded form data, or multipart form data with and without files. Authentication support is described as rich, though the README does not enumerate the schemes.

For the actual signatures, the README points to the official site at restsharp.dev and to the v107+ docs. It also directs questions to StackOverflow under the restsharp tag, to the RestSharp Discord server, and to the @RestSharp account on Twitter. Those are the routes the project itself names, and they are a better source for method names than any reconstruction from a package table.

The Single-Maintainer Support Model

This is the limitation worth reading twice. The README states plainly that RestSharp is an open-source project with a single maintainer, and that you should not expect your issue to be resolved unless it concerns a large group of RestSharp users. It goes further: the best way to resolve your issue is to fix it yourself, fork the repository, and submit a pull request. Sponsorship is offered as a way to motivate the maintainer.

That is an honest statement of project economics, and it should shape how you adopt the library. If your team depends on RestSharp for a production integration and hits a bug that affects only your use case, the documented path is a fork and a pull request, not a support ticket. For a small team with C# capacity, that is workable. For a team without it, the calculus is different.

The maintenance signal is otherwise healthy in the mechanical sense. The repository is not archived, and the last push was on 2026-09-07. The most recent release listed is 114.0.0 on 2026-03-05, following 113.0.0 on 2025-11-28 and 112.1.0 on 2024-10-04. The gap between 112.1.0 and 113.0.0 is roughly fourteen months, and between 113.0.0 and 114.0.0 roughly three months. Release cadence is uneven, which is consistent with a single maintainer working around other commitments.

RestSharp or HttpClient: The Real Difference

The most common comparison is RestSharp against raw HttpClient, and the README answers it directly. RestSharp is a wrapper around HttpClient, not a replacement. Everything RestSharp does, HttpClient can do, because RestSharp is calling into it.

The difference is ergonomics and where the code lives. With HttpClient you build query strings, set content headers, and choose a serializer yourself, and you manage the client lifetime carefully because of socket exhaustion concerns. RestSharp moves the client configuration into RestClientOptions, which the README ties to thread safety, and gives you parameter methods that accept query, URL segment, header, cookie, and body values through one API. It also bundles serialization for JSON, XML, and CSV so you do not wire up a serializer per project.

The trade-off is a dependency and an abstraction. If your project makes a handful of HTTP calls with simple payloads, HttpClient plus System.Text.Json is already in the framework and adds nothing to your dependency graph. RestSharp earns its place when you have many endpoints, mixed parameter types, and a real need for the default-parameter behavior that HttpClient does not offer out of the box.

Upgrade Cost and Licence Implications

Upgrades are the recurring cost. The README devotes a compatibility note to the 107 release precisely because it was disruptive: SimpleJson replaced by System.Text.Json.JsonSerializer, IRestRequest and IRestResponse deprecated in favour of implementing classes, Http and IHttp removed as wrappers, client configuration relocated to RestClientOptions, and a substantially reduced IRestClient interface surface. Code written against pre-107 RestSharp will not compile unchanged.

The version history suggests you should plan for periodic major releases rather than continuous small ones. Moving from 112.1.0 to 113.0.0 to 114.0.0 means three major version boundaries in under two years. The README points to the v107+ docs for migration information, and that is where you should look before bumping a version in a project that has a lot of RestSharp call sites.

On licensing, RestSharp is Apache-2.0, stated in the README and present as LICENSE.txt at the repository root. Apache-2.0 is a permissive licence that permits commercial use and modification, and it includes an explicit patent grant. It also requires that you preserve copyright and licence notices and state significant changes when you redistribute. The project is part of the .NET Foundation. This is a description of the licence text, not legal advice; your own counsel should review how it applies to your distribution model.

Editorial conclusion

Use RestSharp when you want a terse C# API surface for query parameters, JSON bodies, and authentication on top of HttpClient, and you accept that one maintainer handles issues. Do not adopt it if you need a fully supported commercial client or you cannot tolerate breaking changes across major versions. Before upgrading, check the v107+ docs for the RestClientOptions and IRestClient changes, and confirm which serializer package your project references.

Frequently asked questions

Official sources

1. License: Apache-2.0
2. Project website
3. README
4. Releases
5. restsharp/RestSharp on GitHub