Guides / Go
Invoices, contracts, reports, certificates: every product eventually needs PDFs, and Go PDF libraries make you hand-position every box. RasterKit prints through real Chromium instead — write ordinary HTML and CSS, POST it, get a finished PDF back.
Because it's a print pipeline rather than a drawing API, you keep your existing templates and stylesheets: flexbox, grid, web fonts, page-break CSS, repeating headers and footers with page numbers all just work.
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.
package main
import (
"bytes"
"fmt"
"io"
"net/http"
"os"
"time"
)
func main() {
body := []byte(`{"url": "https://example.com/invoice/42", "format": "A4", "print_background": true}`)
req, _ := http.NewRequest("POST", "https://rasterkit.com/v1/pdf", bytes.NewReader(body))
req.Header.Set("x-api-key", os.Getenv("RASTERKIT_API_KEY"))
req.Header.Set("content-type", "application/json")
client := &http.Client{Timeout: 60 * time.Second}
res, err := client.Do(req)
if err != nil {
panic(err)
}
defer res.Body.Close()
data, _ := io.ReadAll(res.Body)
if res.StatusCode != 200 {
panic(fmt.Sprintf("render failed: %d %s", res.StatusCode, data))
}
os.WriteFile("document.pdf", data, 0644)
fmt.Println("Saved document.pdf")
}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 PDF API reference documents every parameter. The ones people reach for first:
format: "Letter", landscape: true — paper setupfooter_template — page numbers via <span class="pageNumber">print_background: true — keep your CSS backgrounds (on by default)wait_for_selector — wait for charts/data before printingPass footer_template with Chromium's built-in classes, e.g. <span class="pageNumber"></span> / <span class="totalPages"></span>.
Browsers skip backgrounds when printing by default. RasterKit sets print_background: true by default — if you turned it off, turn it back on.
Yes — standard CSS (break-inside: avoid, break-after: page) is respected, and prefer_css_page_size lets your @page rules define the paper size.