API

A PDF API for one cent

Compress, merge and convert from your code. $0.01 per document, the first 100 per month free. No subscription, no minimum.

Get a key Endpoints

The API processes files on the server

Unlike the browser editor, the API sends the file to our server. It is processed in memory, never written to disk and not kept after the response; file names are not stored. For documents that must not leave your network, use the browser or Enterprise.

Authentication

Bearer key in the header

Create a key in your dashboard. It starts with sd_live_ and is shown once: we only store its hash. Send the key with every request:

Authorization: Bearer sd_live_XXXXXXXXXXXXXXXXXXXXXXXX

Request body — multipart/form-data with fields file or a raw file with Content-Type: application/pdf | image/png | image/jpeg. The response is the finished PDF. Limit — 100 MB per file and 50 files per request.

Endpoints

Three operations

POST/api/v1/compress

Compress

Lossless compression: removes Info and XMP metadata and unused objects, rebuilds the document with object streams. The result is never larger than the original.

file: One PDF. Can be sent as a raw body with Content-Type: application/pdf.

curl

curl -X POST https://lockpage.tools/api/v1/compress \
  -H "Authorization: Bearer $LOCKPAGE_KEY" \
  -F file=@contract.pdf \
  -o contract.min.pdf

POST/api/v1/merge

Merge

Merges PDFs in the order of the file fields. 2 to 50 files per request.

file: Repeated field, 2 to 50 PDFs. Order is preserved.

curl

curl -X POST https://lockpage.tools/api/v1/merge \
  -H "Authorization: Bearer $LOCKPAGE_KEY" \
  -F file=@act.pdf \
  -F file=@invoice.pdf \
  -o merged.pdf

POST/api/v1/convert

Convert

The server supports PNG and JPEG → PDF: every image becomes a page. Other directions return 501 not_implemented — for now they work only in the browser.

file: One or more PNG/JPEG images.
to: Target format: pdf. For a raw body use the query parameter ?to=pdf.

curl

curl -X POST "https://lockpage.tools/api/v1/convert?to=pdf" \
  -H "Authorization: Bearer $LOCKPAGE_KEY" \
  -H "Content-Type: image/jpeg" \
  --data-binary @scan.jpg \
  -o scan.pdf

Responses

Success and errors

A successful response is a PDF with usage headers. An error is JSON with a machine code and a human-readable message you can show to users.

200 OK

HTTP/1.1 200 OK
Content-Type: application/pdf
Content-Disposition: attachment; filename="securadoc-merge.pdf"
Cache-Control: no-store
X-Lockpage-Documents: 2
X-Lockpage-Price-Usd-Per-Document: 0.01

%PDF-1.7 …

Error

HTTP/1.1 400 Bad Request Content-Type: application/json { "error": { "code": "bad_request", "message": "merge needs at least two files" } }

HTTP	code	When
400	bad_request	No files, wrong set of files for the operation, damaged PDF
401	unauthorized	No Authorization header, invalid or revoked key
413	too_large	File is larger than 100 MB
415	unsupported_media_type	Input file format is not supported
501	not_implemented	This conversion is not available on the server yet
500	internal	Internal error. Please try again later.

Node.js 20+

const form = new FormData();
form.append("file", new Blob([await fs.readFile("a.pdf")]), "a.pdf");
form.append("file", new Blob([await fs.readFile("b.pdf")]), "b.pdf");

const res = await fetch("https://lockpage.tools/api/v1/merge", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.LOCKPAGE_KEY}` },
  body: form,
});
if (!res.ok) throw new Error((await res.json()).error.message);
await fs.writeFile("merged.pdf", Buffer.from(await res.arrayBuffer()));

Usage

How pricing works

A document is one input file in a successful request: merging three PDFs counts as three documents. Failed requests are free. The first 100 documents each calendar month are free, then $0.01 per document. Your current month's usage is shown in the dashboard.

Documents per month	Cost
up to 100	Free
1,000	$9
10,000	$99
100,000	$999