Generate PDFs in Go

Generate a PDF in Go

POST your HTML and data to /api/v1/generate with your API key, then save the PDF that comes back. Swap in your own HTML or a saved template_id and loop over records to render at scale.

package main

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"
	"os"
)

func main() {
	payload, _ := json.Marshal(map[string]any{
		"html":   "<h1>Invoice {{number}}</h1><p>Billed to {{client}} — total {{total}}</p>",
		"engine": "handlebars",
		"format": "A4",
		"data": map[string]string{
			"number": "INV-001", "client": "Acme Corp", "total": "$2,400.00",
		},
	})

	req, _ := http.NewRequest("POST", "https://pdfgen.com/api/v1/generate", bytes.NewReader(payload))
	req.Header.Set("Authorization", "Bearer pdfg_live_xxx")
	req.Header.Set("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)
	defer res.Body.Close()

	out, _ := os.Create("invoice.pdf")
	defer out.Close()
	io.Copy(out, res.Body)
}

Convert existing HTML to PDF in Go

Already have finished HTML? Skip templating — read an .html file and POST it with net/http and send it with engine: "legacy", which tells the API your markup is final.

package main

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"
	"os"
)

func main() {
	// Your existing, already-styled HTML file.
	html, _ := os.ReadFile("invoice.html")

	payload, _ := json.Marshal(map[string]any{
		"html":   string(html),
		"engine": "legacy",
		"format": "A4",
	})

	req, _ := http.NewRequest("POST", "https://pdfgen.com/api/v1/generate", bytes.NewReader(payload))
	req.Header.Set("Authorization", "Bearer pdfg_live_xxx")
	req.Header.Set("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)
	defer res.Body.Close()

	out, _ := os.Create("invoice.pdf")
	defer out.Close()
	io.Copy(out, res.Body)
}

How it works

1. 1

   Send your HTML + data

   POST an HTML template (with optional Handlebars tokens) and a data object to the API.

2. 2

   We render the PDF

   PDFgen renders it server-side — no headless browser for you to run or scale.

3. 3

   Get the PDF back

   Receive the PDF binary (or a hosted link with export_type:"url") and serve it from Go.

Good to know

• Only the standard library — no cgo and no third-party PDF dependency.
• Stream straight to a browser by copying res.Body into your http.ResponseWriter instead of a file.
• In real code, check each error return; they’re elided here for brevity.

Frequently asked questions

What’s the best way to generate a PDF in Go?

POST your HTML and data to /api/v1/generate with net/http and copy the response body to a file or writer — no cgo or external binary.

Can I stream the PDF to an HTTP response?

Yes — io.Copy from res.Body into your http.ResponseWriter after setting a Content-Type of application/pdf.

Do I need a cgo-based library?

No. The call is plain HTTP, so your build stays pure Go and easy to cross-compile.

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