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Get a fillable PDF of just the form — no nav, no footer in Ruby with Net::HTTP

A fillable PDF of a whole web page still carries the web page around it: the navigation bar, the cookie banner, the footer with forty links. Adding "pdf_form_only": true to a pdf_forms render prunes the document down to just the form — fields with their labels, the group headings, and the title directly above it. What comes out looks like the paper version of the form, not a printout of the website.

Below is a complete, runnable Ruby program using Net::HTTP, no third-party dependency needed. It reads your API key from the SNAPDOK_KEY environment variable — free keys take about thirty seconds and need no card.

require "json"
require "net/http"
require "uri"

uri = URI("https://snapdok.io/v1/render")

res = Net::HTTP.start(uri.host, uri.port, use_ssl: true, read_timeout: 90) do |http|
  req = Net::HTTP::Post.new(uri)
  req["Authorization"] = "Bearer #{ENV.fetch("SNAPDOK_KEY")}"
  req["Content-Type"] = "application/json"
  req.body = JSON.generate({
    url: "https://your-app.com/intake-form",
    format: "pdf",
    pdf_forms: true,
    pdf_form_only: true,
})
  http.request(req)
end

raise "snapdok error #{res.code}: #{res.body}" unless res.is_a?(Net::HTTPSuccess)

File.binwrite("form-only.pdf", res.body)
puts "#{res["X-Form-Extracted"]}  # true = pruned to the form; false = full page"

This flag is best-effort by design, and you should code for that. When the extractor cannot identify a form region it is sure about — no visible controls, a lone search box, a form wrapping the entire page (common on older ASP.NET sites), iframes, JavaScript widget "forms" — it falls back to the full page: the exact bytes pdf_forms alone would have produced, never a half-broken cut. The rule it is built around: better a navigation bar too many than a required field too few.

The response tells you which way it went: X-Form-Extracted: true means the PDF is the pruned form, false means the full page, with the machine reason in X-Form-Extract-Fallback. The flag is ignored unless format is "pdf" and pdf_forms is true, and it is metered as one ordinary render — no extra charge.

Notes for Net::HTTP

Stdlib only — no gems. The traps Net::HTTP is famous for, all handled in the sample: TLS is not automatic (set use_ssl: true or you will POST in the clear to port 80 and get a redirect); the default read_timeout of 60 s is close enough to real render times that raising it is wise; and the response body is a binary-ready String, but write it with File.binwrite — plain File.write on Windows would mangle line-ending bytes in the PDF. Check is_a?(Net::HTTPSuccess): Net::HTTP never raises on HTTP error statuses.

Response headers worth reading

HeaderMeaning
X-Form-Extractedtrue when the prune happened, false on fallback.
X-Form-Extract-FallbackWhy extraction fell back, when it did.
X-Form-FieldsFields placed either way.

Full parameter reference: the docs. Hard numbers on caps and timeouts: limits.

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