CaptureKit Node.js SDK

The official Node.js and TypeScript SDK for the CaptureKit screenshot API.

Capture websites as PNG, JPEG, WebP or PDF, extract their content, or analyse them with AI.

The SDK exposes 7 typed methods, one per documented endpoint, plus a generic request() for anything else.

Requirements

• Node.js 20 or newer

Installation

npm install @capturekitdev/sdk

The SDK works with TypeScript and JavaScript (ES modules). The examples below use TypeScript; JavaScript users can use the same API by omitting TypeScript-only syntax.

Get your API key

Sign up for CaptureKit or sign in to your existing account, then copy your API key from the dashboard. Store it securely, for example in the CAPTUREKIT_API_KEY environment variable, which the client reads by default.

Quick start

import { CaptureKitClient } from "@capturekitdev/sdk";

const client = new CaptureKitClient({ apiKey: process.env.CAPTUREKIT_API_KEY });

const response = await client.content({ url: "https://example.com" });
console.log(response.data);

Every method takes a parameter object that mirrors the API reference (snake_case names, exactly as documented) and an optional RequestOptions object.

Binary responses

Some endpoints return a file (image, PDF…) instead of JSON. Their methods return an ApiResponse, so check kind:

import { writeFile } from "node:fs/promises";

const response = await client.capture({
  url: "https://example.com",
  format: "png",
});
if (response.kind === "binary") {
  await writeFile("screenshot.png", response.bytes);
} else {
  console.log(response.data);
}

Async jobs

Any call accepts is_async: true (useful past the 60-second server limit): the response is then a job_id. waitForJob() polls GET /v1/jobs/{id} until the job reaches a terminal status (CompletedJob, Error, NotFound, BadRequest):

const submitted = await client.content({
  url: "https://example.com",
  is_async: true,
});
const job = await client.waitForJob(submitted.data.job_id, {
  onProgress: (j) => console.log(`${j.status} ${j.progress ?? 0}%`),
});
console.log(JSON.stringify(job.data, null, 2));

GET or POST

Methods use GET when the endpoint supports it: parameters travel in the query string. POST sends the same parameters as a JSON body.

await client.analyze({ url: "test" }, { method: "POST" });

null, undefined and empty arrays are omitted, false and 0 are sent, and arrays repeat the parameter name (a=1&a=2).

Any endpoint

request() reaches any path, including endpoints released after this SDK version:

const response = await client.request("GET", "/v1/usage");

Responses

• JsonResponse — kind: "json", the parsed body in data (pass a type argument to type it: client.content<MyType>(…)).
• BinaryResponse — kind: "binary", the body in bytes and its contentType.

Both keep the buffered rawResponse (status, headers, content type, body bytes).

Errors

import { CaptureKitApiError } from "@capturekitdev/sdk";

try {
  await client.content({ url: "https://example.com" });
} catch (error) {
  if (error instanceof CaptureKitApiError) {
    console.error(error.status, error.message, error.responseBody);
  }
  throw error;
}

Error	When
CaptureKitConfigurationError	Missing API key, invalid options or unsupported method.
CaptureKitSerializationError	A required parameter is missing or a value can't be sent.
CaptureKitTransportError	Network failure or client-side timeout.
CaptureKitApiError	The API answered with a non-2xx status (status, message, responseBody).
CaptureKitResponseDecodingError	A success response could not be decoded.

All of them extend CaptureKitError. Common statuses: 400 invalid parameters, 401 invalid API key, 402 no credits left, 429 rate limit exceeded.

Retries

Requests are retried up to 3 times after a network error, a 408, 500, 502, 503 or 504, or a rate limit — which the API returns as 401 (or 429) with a Rate limit exceeded message. Per-key quota errors (…: quota daily) are not retried, nor are 400, 402, 404 or client-side timeouts. The delay starts at 1 second and grows 1.5× per retry (capped at 30 seconds); a Retry-After header wins.

const client = new CaptureKitClient({ maxRetries: 5, retryDelay: 500 });

// or for one request
await client.content({ url: "https://example.com" }, { maxRetries: 0 });

Batch requests

batch() runs a task per item with at most 10 in flight (concurrency), and returns one result per item in input order, shaped like Promise.allSettled. One failure never stops the others.

const inputs = [
  "https://example.com",
  "https://www.capturekit.dev",
  "https://github.com",
];
const results = await client.batch(inputs, (url) => client.content({ url }), {
  concurrency: 5,
});

for (const result of results) {
  if (result.status === "fulfilled") console.log(result.value.data);
  else console.error(inputs[result.index], result.reason);
}

Constant	Default	Description
DEFAULT_CONCURRENCY	10	Tasks run at the same time by batch
DEFAULT_TIMEOUT_MS	120000	Request timeout (milliseconds)
MAX_RETRIES	3	Retry attempts after a network error, a 408/5xx or a rate limit
RETRY_BACKOFF_FACTOR	1.5	Exponential backoff multiplier
DEFAULT_RETRY_DELAY_MS	1000	Delay before the first retry (milliseconds)

Timeouts and cancellation

const client = new CaptureKitClient({ timeout: 60_000 }); // default 120000 ms, 0 disables

await client.content(
  { url: "https://example.com" },
  {
    signal: AbortSignal.timeout(30_000),
  },
);

Advanced: custom Fetch transport

import { CaptureKitClient, type CaptureKitFetch } from "@capturekitdev/sdk";

const loggingFetch: CaptureKitFetch = async (input, init) => {
  const response = await fetch(input, init);
  console.log(init.method, String(input), response.status);
  return response;
};

const client = new CaptureKitClient({ fetch: loggingFetch });

Endpoints

7 methods, generated from the OpenAPI document.

Method	HTTP	Description
analyze()	GET / POST /v1/analyze	AI Content API analyzes any webpage and returns AI insights summary, value proposition, features, categories, use cases, and optional conta…
capture()	GET / POST /v1/capture	Browser-like Screenshot API that captures webpages as PNG/JPEG/WebP or PDF for previews, QA, reporting, monitoring, and archiving no headle…
content()	GET / POST /v1/content	CaptureKit Content API extracts structured webpage data, metadata, links, HTML/Markdown: in one request for SEO, monitoring, indexing and a…
jobs()	GET /v1/jobs/{id}	Poll the status, progress (0–100) and result of a job started with is_async=true. Polling is free. Poll until status is terminal: Completed…
stats()	GET /v1/stats	Infrastructure health for an engine or endpoint over the last hour. Not scoped to your account or tenant. Enabled per account: HTTP 403 mea…
usage()	GET /v1/usage	Retrieve real-time usage statistics and credit balance for your CaptureKit account.
websiteCrawler()	GET / POST /v1/website/crawler	Website Crawler API fetches raw HTML from any webpage in request mode (no rendering) for fast scraping, audits, monitoring, and link/metada…

All CaptureKit SDKs

SDK	Package	Install
Node.js	@capturekitdev/sdk	npm install @capturekitdev/sdk
Python	capturekitdev	pip install capturekitdev
Go	capturekit-go	go get github.com/capturekitdev/capturekit-go
.NET	CaptureKit	dotnet add package CaptureKit
Ruby	capturekitdev	gem install capturekitdev
PHP	capturekitdev/sdk	composer require capturekitdev/sdk
Java	capturekit-java	build from source, see its README
CLI	@capturekitdev/cli	npm install -g @capturekitdev/cli
MCP server	@capturekitdev/mcp	npx -y @capturekitdev/mcp

License

MIT — see LICENSE.