# ASP.NET Core (/quickstarts/aspnet-core) Related: [Node.js](/quickstarts/nodejs.md), [Next.js](/quickstarts/nextjs.md), [Express](/quickstarts/express.md), [NestJS](/quickstarts/nestjs.md), [Fastify](/quickstarts/fastify.md), [Hono](/quickstarts/hono.md) ## Prerequisites [#prerequisites] * .NET 6.0+ * A Firecrawl API key — [get one free](https://www.firecrawl.dev/app/api-keys) ## Configuration [#configuration] Add your API key to `appsettings.json`: ```json { "Firecrawl": { "ApiKey": "fc-YOUR-API-KEY", "BaseUrl": "https://api.firecrawl.dev/v2" } } ``` Or use environment variables / user secrets: ```bash export Firecrawl__ApiKey=fc-YOUR-API-KEY ``` ## Create a service [#create-a-service] Create `Services/FirecrawlService.cs`: ```csharp using System.Net.Http.Headers; using System.Text; using System.Text.Json; public class FirecrawlService { private readonly HttpClient _http; private readonly string _baseUrl; public FirecrawlService(IConfiguration config) { _baseUrl = config["Firecrawl:BaseUrl"] ?? "https://api.firecrawl.dev/v2"; _http = new HttpClient(); _http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", config["Firecrawl:ApiKey"]); } public async Task SearchAsync(string query, int limit = 5) { var content = new StringContent( JsonSerializer.Serialize(new { query, limit }), Encoding.UTF8, "application/json"); var response = await _http.PostAsync($"{_baseUrl}/search", content); response.EnsureSuccessStatusCode(); return JsonDocument.Parse(await response.Content.ReadAsStringAsync()); } public async Task ScrapeAsync(string url) { var content = new StringContent( JsonSerializer.Serialize(new { url }), Encoding.UTF8, "application/json"); var response = await _http.PostAsync($"{_baseUrl}/scrape", content); response.EnsureSuccessStatusCode(); return JsonDocument.Parse(await response.Content.ReadAsStringAsync()); } public async Task InteractAsync(string url, string prompt, string? followUp = null) { // 1. Scrape to open a browser session var scrapeContent = new StringContent( JsonSerializer.Serialize(new { url, formats = new[] { "markdown" } }), Encoding.UTF8, "application/json"); var scrapeRes = await _http.PostAsync($"{_baseUrl}/scrape", scrapeContent); scrapeRes.EnsureSuccessStatusCode(); var scrapeDoc = JsonDocument.Parse(await scrapeRes.Content.ReadAsStringAsync()); var scrapeId = scrapeDoc.RootElement .GetProperty("data").GetProperty("metadata").GetProperty("scrapeId").GetString(); // 2. Send first prompt var firstPrompt = new StringContent( JsonSerializer.Serialize(new { prompt }), Encoding.UTF8, "application/json"); await _http.PostAsync($"{_baseUrl}/scrape/{scrapeId}/interact", firstPrompt); // 3. Send follow-up prompt JsonDocument? result = null; if (followUp != null) { var followUpContent = new StringContent( JsonSerializer.Serialize(new { prompt = followUp }), Encoding.UTF8, "application/json"); var followUpRes = await _http.PostAsync( $"{_baseUrl}/scrape/{scrapeId}/interact", followUpContent); followUpRes.EnsureSuccessStatusCode(); result = JsonDocument.Parse(await followUpRes.Content.ReadAsStringAsync()); } // 4. Close the session await _http.DeleteAsync($"{_baseUrl}/scrape/{scrapeId}/interact"); return result ?? scrapeDoc; } } ``` ## Register and use [#register-and-use] In `Program.cs`: ```csharp var builder = WebApplication.CreateBuilder(args); builder.Services.AddSingleton(); var app = builder.Build(); app.MapPost("/api/search", async (FirecrawlService firecrawl, SearchRequest req) => { var result = await firecrawl.SearchAsync(req.Query, req.Limit); return Results.Ok(result.RootElement); }); app.MapPost("/api/scrape", async (FirecrawlService firecrawl, ScrapeRequest req) => { var result = await firecrawl.ScrapeAsync(req.Url); return Results.Ok(result.RootElement); }); app.MapPost("/api/interact", async (FirecrawlService firecrawl, InteractRequest req) => { var result = await firecrawl.InteractAsync(req.Url, req.Prompt, req.FollowUp); return Results.Ok(result.RootElement); }); app.Run(); record SearchRequest(string Query, int Limit = 5); record ScrapeRequest(string Url); record InteractRequest(string Url, string Prompt, string? FollowUp = null); ``` ## Run it [#run-it] ```bash dotnet run ``` ## Test it [#test-it] ```bash # Search the web curl -X POST http://localhost:5000/api/search \ -H "Content-Type: application/json" \ -d '{"query": "firecrawl web scraping"}' # Scrape a page curl -X POST http://localhost:5000/api/scrape \ -H "Content-Type: application/json" \ -d '{"url": "https://example.com"}' # Interact with a page curl -X POST http://localhost:5000/api/interact \ -H "Content-Type: application/json" \ -d '{"url": "https://www.amazon.com", "prompt": "Search for iPhone 16 Pro Max", "followUp": "Click on the first result and tell me the price"}' ``` ## Next steps [#next-steps] Search the web and get full page content All scrape options including formats, actions, and proxies Click, fill forms, and extract dynamic content Complete REST API documentation