Advanced rendering

Chromium, Firefox, and WebKit

Set engine to chromium, firefox, orwebkit. Each request gets a fresh isolated context. PDF andimage.optimize_for_speed require Chromium; normal image and document extraction work across all three engines.

{
  "url": "https://example.com",
  "engine": "webkit",
  "output": "avif",
  "viewport": { "width": 1440, "height": 900 },
  "image": { "quality": 82, "width": 1200 }
}

Actions and assertions

Up to 32 actions run in order after navigation and the initial wait. Supported types are click, hover, fill,press, select, scroll, wait,hide, and javascript. Assertions run after full-page preparation and fail with a typed, non-retryable error.

{
  "url": "https://example.com/search",
  "output": "png",
  "full_page": false,
  "actions": [
    { "type": "fill", "selector": "input[name=q]", "value": "viper" },
    { "type": "press", "key": "Enter" },
    { "type": "wait", "selector": "[data-results]", "timeout_ms": 10000 },
    { "type": "hide", "selector": ".floating-banner" }
  ],
  "assertions": {
    "content_includes": ["Results"],
    "content_excludes": ["Access denied"],
    "request_failures": ["*/critical-api/*"]
  }
}

Network and browser emulation

network can disable target-page JavaScript and accepts a user agent, geolocation, up to 64 cookies, URL block patterns, resource-type blocks, CSP bypass, and HTTPS-error handling. Browser controls remain available when target scripts are disabled. Hosted routing still validates every URL, redirect, DNS answer, and subresource against the SSRF policy. Custom Authorization and Cookie headers never cross the initial origin.

{
  "url": "https://example.com",
  "network": {
    "java_script_enabled": false,
    "user_agent": "ViperCapture QA/1.0",
    "geolocation": { "latitude": 40.7128, "longitude": -74.006 },
    "block_url_patterns": ["**/analytics/**"],
    "block_resource_types": ["media", "font"]
  },
  "environment": {
    "device": "iphone_14",
    "color_scheme": "dark",
    "reduced_motion": "reduce",
    "locale": "en-US",
    "timezone": "America/New_York"
  }
}

Animated full-page output and viewport video

WebM, MP4, and GIF record 1–30 seconds and cost one credit. Withfull_page=true, ViperCapture captures the prepared document once and encodes a smooth top-to-bottom pan over the chosen duration. Full-page GIF and WebM can preserve transparency. Withfull_page=false, it records the live viewport and optionally performs stepped scrolling. MP4 never supports transparency.

{
  "url": "https://example.com",
  "output": "webm",
  "full_page": true,
  "video": {
    "duration_ms": 8000,
    "transparent_background": true
  }
}

Diagnostics and deterministic rendering

diagnostics.bundle=true returns a ZIP containing the normal artifact, manifest, and bounded console/network reports. HAR and WARC are opt-in; a redacted Playwright trace is available for non-video output. Sensitive request headers, credentials, fragments, and query strings are removed from diagnostic routing records.

Deterministic mode fixes time and randomness, disables motion, and can wait for fonts. Use it for regression tests and pair it with assertions when a silent visual fallback would be unsafe.

{
  "url": "https://example.com",
  "output": "png",
  "deterministic": {
    "enabled": true,
    "timestamp_ms": 1700000000000,
    "random_seed": 42,
    "wait_for_fonts": true
  },
  "diagnostics": {
    "bundle": true,
    "include_har": true,
    "include_warc": true
  }
}

Artifact certification and page slices

certification.enabled=true returns a ZIP with the artifact, SHA-256 digest, render metadata, Ed25519 signature, and public key. Fetch the current verification key from GET /v1/certification/public-key. Certification cannot be combined with a viewport pack.

For tall PNG, JPEG, WebP, or AVIF captures, slices returns a manifest ZIP of bounded vertical images. Choose a slice height from 100 to 10,000 CSS pixels and an overlap smaller than the slice height.

{
  "url": "https://example.com/long-report",
  "output": "avif",
  "full_page": true,
  "slices": { "height": 1800, "overlap": 120 },
  "certification": { "enabled": false }
}

Expanded PDF and DOM output

Print PDF supports A0–A6, Legal, Letter, and Tabloid paper, portrait or landscape orientation, bounded header/footer templates, margins, and page ranges selecting at most 50 pages. Opt-in tagged output asks Chromium for document structure used by assistive technology; it depends on source markup and is not PDF/UA certification. Single-page PDF retains the 20,000-CSS-pixel safety ceiling. HTML and Markdown can include bounded open shadow roots with include_shadow_dom=true.