Poll an async PDF render with curl

?wait=false makes the POST answer at once with a 202 ticket: id, status queued, and two urls, poll and download. The loop below asks the poll url once a second; ready means the download url has the document. A failed render ends the loop with the endpoint's error in the poll body.

The recipe

ORIGIN="https://webcapture.io"

TICKET=$(curl -sS -X POST "$ORIGIN/v1/convert?wait=false" \
  -H "Authorization: Bearer wc_your_key" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://example.com/"}')
echo "$TICKET"
# {"id": "cnv_02b8c9d9", "status": "queued",
#  "poll": ".../v1/conversions/cnv_02b8c9d9",
#  "download": ".../v1/conversions/cnv_02b8c9d9.pdf"}

POLL=$(printf '%s' "$TICKET" | sed -E 's/.*"poll": *"([^"]+)".*/\1/')
DOWNLOAD=$(printf '%s' "$TICKET" | sed -E 's/.*"download": *"([^"]+)".*/\1/')

while :; do
  ROW=$(curl -sS -H "Authorization: Bearer wc_your_key" "$POLL")
  STATUS=$(printf '%s' "$ROW" | sed -E 's/.*"status": *"([^"]+)".*/\1/')
  [ "$STATUS" = "queued" ] || [ "$STATUS" = "rendering" ] || break
  sleep 1
done
[ "$STATUS" = "ready" ] || { echo "render failed: $ROW" >&2; exit 1; }

curl -sS -H "Authorization: Bearer wc_your_key" -o page.pdf "$DOWNLOAD"

The guard after the loop turns a failed render into exit 1 with the endpoint's own message, so a cron job sees the difference between a slow page and a broken one. A ready row adds attempts and bytes to the status, so the caller knows the document's size before it downloads; the one-second pace is the endpoint's guidance for interactive scripts, and batch jobs can poll less often.

Same-key GET: 401 without it; 404 for another key.

The fields this recipe uses

• url: the page address to render, a public http(s) URL; ?wait=false is a query parameter on the endpoint, not a body field.

Related

• Next: Get a free key to run this curl recipe, or read the API docs.
• More recipes: curl: convert from a URL, Python: poll an async render, Node: poll an async render.
• The webcapture API reference: every field the convert endpoint admits, with the response shapes and the error table.
• The recipes hub: the same endpoint in the other languages.
• Going deeper: the n8n, Zapier, and Make guides show the same async ticket in each platform's step format.
• The free URL to PDF tool: try the render in a browser before you wire the call.

Method

Source: convert field reference, checked 2026-10-05. Corrections.