前提条件#
- .NET 6.0+
- Firecrawl APIキー — 無料で取得できます
Webを検索#
Firecrawl は、HttpClient を使って REST API 経由で .NET から利用できます。
using System.Net.Http.Headers;using System.Text;using System.Text.Json;var apiKey = Environment.GetEnvironmentVariable("FIRECRAWL_API_KEY");var client = new HttpClient();client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);var content = new StringContent( JsonSerializer.Serialize(new { query = "firecrawl web scraping", limit = 5 }), Encoding.UTF8, "application/json");var response = await client.PostAsync("https://api.firecrawl.dev/v2/search", content);var json = await response.Content.ReadAsStringAsync();Console.WriteLine(json);レスポンス例
{ "success": true, "data": { "web": [ { "url": "https://docs.firecrawl.dev", "title": "Firecrawl Documentation", "markdown": "# Firecrawl\n\nFirecrawl is a web scraping API..." } ] }}ページをスクレイピング#
var scrapeContent = new StringContent( JsonSerializer.Serialize(new { url = "https://example.com" }), Encoding.UTF8, "application/json");var scrapeResponse = await client.PostAsync("https://api.firecrawl.dev/v2/scrape", scrapeContent);var scrapeJson = await scrapeResponse.Content.ReadAsStringAsync();using var doc = JsonDocument.Parse(scrapeJson);var markdown = doc.RootElement.GetProperty("data").GetProperty("markdown").GetString();Console.WriteLine(markdown);レスポンス例
{ "success": true, "data": { "markdown": "# Example Domain\n\nThis domain is for use in illustrative examples...", "metadata": { "title": "Example Domain", "sourceURL": "https://example.com" } }}ページをInteractする#
ブラウザセッションを開始し、自然言語のプロンプトでページをInteractした後、セッションを終了します。
ステップ1 — セッションを開始するためにスクレイピングする#
var sessionContent = new StringContent( JsonSerializer.Serialize(new { url = "https://www.amazon.com", formats = new[] { "markdown" } }), Encoding.UTF8, "application/json");var sessionResponse = await client.PostAsync("https://api.firecrawl.dev/v2/scrape", sessionContent);var sessionJson = await sessionResponse.Content.ReadAsStringAsync();using var sessionDoc = JsonDocument.Parse(sessionJson);var scrapeId = sessionDoc.RootElement .GetProperty("data") .GetProperty("metadata") .GetProperty("scrapeId") .GetString();Console.WriteLine($"scrapeId: {scrapeId}");ステップ 2 — 操作を送信#
var interactUrl = $"https://api.firecrawl.dev/v2/scrape/{scrapeId}/interact";// 商品を検索するvar searchBody = new StringContent( JsonSerializer.Serialize(new { prompt = "Search for iPhone 16 Pro Max" }), Encoding.UTF8, "application/json");var searchResult = await client.PostAsync(interactUrl, searchBody);Console.WriteLine(await searchResult.Content.ReadAsStringAsync());// 最初の結果をクリックするvar clickBody = new StringContent( JsonSerializer.Serialize(new { prompt = "Click on the first result and tell me the price" }), Encoding.UTF8, "application/json");var clickResult = await client.PostAsync(interactUrl, clickBody);Console.WriteLine(await clickResult.Content.ReadAsStringAsync());ステップ 3 — セッションを停止する#
await client.DeleteAsync(interactUrl);Console.WriteLine("セッションが停止しました");再利用可能なクライアントクラス#
繰り返し使う場合は、API を型付きクライアントとしてラップします。
using System.Net.Http.Headers;using System.Text;using System.Text.Json;public class FirecrawlClient{ private readonly HttpClient _http; private const string BaseUrl = "https://api.firecrawl.dev/v2"; public FirecrawlClient(string apiKey) { _http = new HttpClient(); _http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey); } private async Task<JsonDocument> PostAsync(string endpoint, object payload) { var content = new StringContent( JsonSerializer.Serialize(payload), Encoding.UTF8, "application/json" ); var response = await _http.PostAsync($"{BaseUrl}{endpoint}", content); response.EnsureSuccessStatusCode(); var json = await response.Content.ReadAsStringAsync(); return JsonDocument.Parse(json); } public async Task<JsonDocument> ScrapeAsync(string url) { return await PostAsync("/scrape", new { url }); } public async Task<JsonDocument> SearchAsync(string query, int limit = 5) { return await PostAsync("/search", new { query, limit }); }}// 使用例var firecrawl = new FirecrawlClient(Environment.GetEnvironmentVariable("FIRECRAWL_API_KEY")!);var result = await firecrawl.SearchAsync("firecrawl web scraping");Console.WriteLine(result.RootElement);