CaptureKit Java SDK

The official Java 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, each with a parameter builder, plus a generic request(). It uses java.net.http.HttpClient and Jackson.

Requirements

• Java 17 or newer

Installation

The SDK is not on Maven Central. Build it from source, which installs it in your local Maven repository:

git clone https://github.com/capturekitdev/capturekit-java.git
cd capturekit-java
mvn -q install -DskipTests

Then add it to your project. Maven:

<dependency>
  <groupId>dev.capturekit</groupId>
  <artifactId>capturekit</artifactId>
  <version>0.1.0</version>
</dependency>

Gradle, with mavenLocal() in your repositories:

implementation("dev.capturekit:capturekit:0.1.0")

Get your API key

Sign up for CaptureKit or sign in, then copy your API key from the dashboard. CaptureKitClient.fromEnv() reads the CAPTUREKIT_API_KEY environment variable.

Quick start

import dev.capturekit.ApiResponse;
import dev.capturekit.CaptureKitClient;
import dev.capturekit.params.ContentParams;

CaptureKitClient client = CaptureKitClient.fromEnv();
ApiResponse response = client.content(ContentParams.builder().url("https://example.com").build());
System.out.println(response.json().toPrettyString());

Parameter builders mirror the API reference; build() checks required parameters. Use response.as(MyType.class) to map the JSON onto your own types.

Binary responses

Endpoints that return a file (image, PDF…) give you the bytes; isJson() tells both cases apart:

ApiResponse response = client.capture(CaptureParams.builder().url("https://example.com").format("png").build());
if (!response.isJson()) {
  java.nio.file.Files.write(java.nio.file.Path.of("screenshot.png"), response.bytes());
}

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 a terminal status (CompletedJob, Error, NotFound, BadRequest):

ApiResponse submitted = client.content(ContentParams.builder().url("https://example.com").isAsync(true).build());
ApiResponse job = client.waitForJob(
    submitted.json().get("job_id").asText(),
    Duration.ofSeconds(3),
    Duration.ofHours(12),
    progress -> System.out.println(progress.path("status").asText() + " " + progress.path("progress").asInt()));

GET or POST

Methods use GET when the endpoint supports it (query string). POST sends the same parameters as JSON:

client.analyze(AnalyzeParams.builder().url("test").build(), RequestOptions.method("POST"));

Any endpoint

ApiResponse response = client.request("GET", "/v1/usage", Map.of());

Errors

try {
  client.content(ContentParams.builder().url("https://example.com").build());
} catch (CaptureKitApiException e) {
  System.err.println(e.status() + ": " + e.getMessage());
}

Exception	When
CaptureKitConfigurationException	Missing API key, invalid options or unsupported method.
CaptureKitSerializationException	A required parameter is missing or a value can't be sent.
CaptureKitTransportException	Network failure, timeout or interruption.
CaptureKitApiException	Non-2xx status (status(), errorMessage(), responseBody(), rawResponse()).
CaptureKitResponseDecodingException	A success response could not be decoded.

All of them extend the unchecked CaptureKitException.

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.

CaptureKitClient client = CaptureKitClient.builder().maxRetries(5).retryDelay(Duration.ofMillis(500)).build();
client.content(ContentParams.builder().url("https://example.com").build(), RequestOptions.builder().maxRetries(0).build()); // one request without retries

Batch requests

batch() runs a function per item on 10 threads (concurrency) and returns one BatchResult per item, in input order. A failing item never stops the others.

List<String> inputs = List.of("https://example.com", "https://www.capturekit.dev", "https://github.com");
List<BatchResult<ApiResponse>> results = client.batch(inputs, 5, value ->
    client.content(ContentParams.builder().url(value).build()));
for (BatchResult<ApiResponse> result : results) {
  if (result.ok()) {
    System.out.println(result.value().json());
  } else {
    System.err.println(inputs.get(result.index()) + ": " + result.error().getMessage());
  }
}

Constant	Default	Description
CaptureKitClient.DEFAULT_CONCURRENCY	10	Tasks run at the same time by batch
CaptureKitClient.DEFAULT_TIMEOUT	Duration.ofSeconds(120)	Request timeout
CaptureKitClient.MAX_RETRIES	3	Retry attempts after a network error, a 408/5xx or a rate limit
CaptureKitClient.RETRY_BACKOFF_FACTOR	1.5	Exponential backoff multiplier
CaptureKitClient.DEFAULT_RETRY_DELAY	Duration.ofSeconds(1)	Delay before the first retry

Configuration

CaptureKitClient client = CaptureKitClient.builder()
    .apiKey(System.getenv("CAPTUREKIT_API_KEY"))
    .timeout(Duration.ofSeconds(60)) // default 120 s, null disables
    .header("X-Trace", "abc")
    .transport(CaptureKitTransport.fromHttpClient(myHttpClient)) // optional
    .build();

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.