PDFops API reference

Endpoints

• POST /api/fill-form

  Fill AcroForm fields in a PDF template you upload. Multipart request with pdf (binary) and fields (JSON). Returns the filled PDF as application/pdf.

• POST /api/merge

  Merge two or more PDFs into one. Multipart request with repeated pdf fields, concatenated in field order. Returns the merged PDF as application/pdf.

• POST /api/waitlist

  Submit a waitlist entry for higher-quota keys. JSON body with use case, current solution, expected volume, pay range, optional email + message. Returns { "ok": true }.

Contract — applies to every endpoint

• Base URL: https://pdfops.dev
• Auth: None during beta. Anonymous, per-IP rate-limited.
• Rate limit: 100 successful (2xx) requests per IP per calendar month (UTC). The middleware only counts accepted requests; 4xx and 5xx don't consume budget.
• Rate-limit response: 429 Too Many Requests with Retry-After seconds-until-next-month.
• Request body format: multipart/form-data for PDF-binary endpoints (/fill-form, /merge); application/json for /waitlist.
• Response on success: 200 OK with application/pdf body (binary endpoints) or application/json with { "ok": true } (waitlist).
• Response on validation failure: 400 Bad Request with application/json body { "error": "<code>", "details": "<explanation>" }.
• Response on server error: 500 Internal Server Error with the same JSON shape. Treat as retryable.

Fillable PDFs — quick start

Don't have a fillable PDF handy? Grab the sample invoice-template.pdf — it has customer_name + total AcroForm fields ready to fill via the curl example on each docs page.

For tax forms (W-9, W-8BEN, I-9) the IRS publishes AcroForm-ready PDFs at irs.gov/forms-instructions — just rename the default IRS field names to something predictable (see the W-9 walkthrough) and your code survives the annual form refresh.

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