Guides / C#
Maintaining your own headless-browser fleet for screenshots means babysitting Chromium versions, memory leaks, fonts, and proxy rules. RasterKit turns all of that into a single HTTPS call: send a URL from your C# code, get back finished image bytes.
The engine runs real Chromium, so modern CSS, web fonts and JavaScript-rendered pages come out exactly as users see them. Flags like full_page, device=mobile, dark_mode and block_cookie_banners handle the cases that make DIY screenshotting painful.
Sign up free (magic link, no card) — your key is shown right after sign-in. You get 100 renders/month free across screenshots, PDFs, and images.
using System.Text;
var client = new HttpClient { Timeout = TimeSpan.FromSeconds(60) };
client.DefaultRequestHeaders.Add("x-api-key",
Environment.GetEnvironmentVariable("RASTERKIT_API_KEY"));
var body = new StringContent(
"""{"url": "https://example.com", "full_page": true, "format": "png"}""",
Encoding.UTF8, "application/json");
var res = await client.PostAsync("https://rasterkit.com/v1/screenshot", body);
var bytes = await res.Content.ReadAsByteArrayAsync();
if (!res.IsSuccessStatusCode)
throw new Exception($"Render failed: {(int)res.StatusCode} {Encoding.UTF8.GetString(bytes)}");
await File.WriteAllBytesAsync("screenshot.png", bytes);
Console.WriteLine("Saved screenshot.png");The response body is the file itself — no JSON envelope to unwrap, no second download request. Errors come back as JSON with a stable error code.
The Screenshot API reference documents every parameter. The ones people reach for first:
full_page: true — capture the whole scroll height (lazy content auto-scrolled in)device: "mobile" — real iPhone-class viewport and user agentdark_mode: true — render with prefers-color-scheme: darkcache_ttl: 86400 — repeat captures become instant and freePass "full_page": true. RasterKit auto-scrolls the page first so lazy-loaded images and infinite-scroll content are included.
Yes — every render runs in real Chromium with JS enabled. Use wait_until: "networkidle", wait_for_selector, or delay_ms for late-rendering apps.
Typical p50 is 1.5–3 s for a normal page (sync request). Add cache_ttl and repeated captures of the same URL return instantly and free.