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To send cookies or other custom headers with an HTMLCSStoImage screenshot request, add them to the headers parameter. For a JSON request, pass a flat object whose keys are header names and whose values are strings. For a form request, repeat headers once per header in name:value form. This applies to URL screenshots, not HTML/CSS or template renders.
Set headers in a JSON request
Send a POST request to https://hcti.io/v1/image, authenticated with HTTP Basic authentication: use your API ID as the username and API key as the password. Set url to the page to capture and provide a flat headers object:
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{
"url": "https://example.com/account",
"headers": {
"Cookie": "session=short-lived-session-value",
"X-Preview-Mode": "enabled"
}
}Header names are object keys; values must be strings. Nested objects and arrays are unsupported. Supply either url or html for image creation, not both. Custom request headers are for URL screenshots.
Send headers with a form request
With form-encoded data, repeat the headers field for every header. The service splits each value at its first colon, so colons after that point remain part of the header value.
#1 Best Overall
- CRISP CLARITY: This 23.8″ Philips V line monitor delivers crisp Full HD 1920x1080 visuals. Enjoy movies, shows and videos with remarkable detail
- INCREDIBLE CONTRAST: The VA panel produces brighter whites and deeper blacks. You get true-to-life images and more gradients with 16.7 million colors
- THE PERFECT VIEW: The 178/178 degree extra wide viewing angle prevents the shifting of colors when viewed from an offset angle, so you always get consistent colors
- WORK SEAMLESSLY: This sleek monitor is virtually bezel-free on three sides, so the screen looks even bigger for the viewer. This minimalistic design also allows for seamless multi-monitor setups that enhance your workflow and boost productivity
- A BETTER READING EXPERIENCE: For busy office workers, EasyRead mode provides a more paper-like experience for when viewing lengthy documents
curl -X POST https://hcti.io/v1/image
-u 'API_ID:API_KEY'
--data-urlencode 'url=https://example.com/account'
--data-urlencode 'headers=Cookie:session=short-lived-session-value'
--data-urlencode 'headers=X-Preview-Mode:enabled'Replace the example credentials and URL with your own. Keep the API ID and key on the server side rather than exposing them in browser code.
Control which origins receive headers
By default, custom headers accompany top-level navigation to the requested URL’s origin. To send them to another authorized origin, include that exact origin in additional_header_origins. An origin includes its scheme, host, and optional port; changing the scheme or port means a different origin.
Rank #2
- CRISP CLARITY: This 22 inch class (21.5″ viewable) Philips V line monitor delivers crisp Full HD 1920x1080 visuals. Enjoy movies, shows and videos with remarkable detail
- 100HZ FAST REFRESH RATE: 100Hz brings your favorite movies and video games to life. Stream, binge, and play effortlessly
- SMOOTH ACTION WITH ADAPTIVE-SYNC: Adaptive-Sync technology ensures fluid action sequences and rapid response time. Every frame will be rendered smoothly with crystal clarity and without stutter
- INCREDIBLE CONTRAST: The VA panel produces brighter whites and deeper blacks. You get true-to-life images and more gradients with 16.7 million colors
- THE PERFECT VIEW: The 178/178 degree extra wide viewing angle prevents the shifting of colors when viewed from an offset angle, so you always get consistent colors
Headers reach CSS, image, JavaScript, and other subrequests only if include_headers_on_subrequests is true. They are then limited to the requested origin and any listed additional origins. Leave this option false if only the main page needs the header; doing so helps avoid sending credentials to third-party resources or cross-origin redirects.
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Respect header limits and restrictions
The API documentation sets these limits for custom headers:
Rank #3
- Clear visuals. Fluid motion: A 144Hz refresh rate and 1ms MPRT deliver smooth, tear‑free motion across work, gaming, and streaming for clearer, more fluid viewing.
- Eye comfort: TÜV Rheinland 3‑star* certification reduces harmful blue light while preserving stunning color quality without compromise. *TÜV Rheinland 3-star eye comfort certification.
- Wide viewing angle: Get consistent views across a wide 178° /178° viewing angle.
- In-Plane Switching (IPS): See excellent color accuracy and consistency across wide viewing angles with In-plane Switching (IPS) technology.
- Ultra-thin bezels: Maximize your viewing experience with thin bezels.
- Up to 20 headers per request.
- Header names must be unique without regard to case and can be up to 512 ASCII characters.
- Values can be up to 8,192 UTF-8 bytes.
- Control characters are disallowed except horizontal tab.
Hop-by-hop, proxy, forwarding, connection, host, infrastructure-controlled, and certain prefixed headers are restricted. Invalid, duplicate, restricted, or oversized headers produce a request error.
Use session cookies for authorized pages
For a page you are authorized to access, send a short-lived session cookie or authorization token in headers. HTMLCSStoImage states: “The API does not automate an interactive login flow.” If the page offers an embed that provides the content you need, using that may avoid rendering a signed-in page.
Rank #4
- CURVED FOR ENHANCED ENGAGEMENT: An immersive viewing experience with a curved monitor that wraps more closely around your field of vision; It creates a wider view, enhancing depth perception and minimizing peripheral distraction
- SMOOTH PERFORMANCE FOR SEAMLESS CONTENT: Stay in the action when playing games, watching videos, or working on creative projects; The 100Hz refresh rate reduces lag and motion blur so you don't miss a thing in fast-paced moments¹
- MORE GAMING POWER: Gain the edge with optimizable game settings; Color and image contrast can be adjusted to see scenes more vividly and spot enemies hiding in the dark; Game Mode adjusts any game to fill the screen so you can view every detail²
- KEEP IT EASY ON THE EYES: Care for your eyes and stay comfortable, even during long sessions; Advanced eye comfort technology certified by TÜV reduces eye strain by minimizing blue light and reducing irritating screen flicker²
- INCREASED VERSATILITY: Connect to more; Plug devices straight into your monitor for increased flexibility, making your computing environment even more convenient
Treat the API key like a password, and scope it to the operations your application needs. Use narrowly scoped, short-lived page credentials when possible. Avoid placing secrets in create-and-render URLs: URLs can appear in browser history, access logs, analytics, and referrer data.
Sign requests containing headers carefully
If you use a signed create-and-render URL, represent headers as repeated query parameters in name:value form. Every repeated headers parameter must be included in the HMAC calculation in its exact order and encoding. Keep signing on your server and do not expose the API key in client-side code. See the HTMLCSStoImage documentation for the service’s API guidance.
Best Value
- 【INTEGRATED SPEAKERS】Whether you're at work or in the midst of an intense gaming session, our built-in speakers provide rich and seamless audio, all while keeping your desk clutter-free.
- 【EASY ON THE EYES】 Protect your eyes and enhance your comfort with Blue-Light Shift technology. This feature reduces harmful blue light emissions from your screen, helping to alleviate eye strain during long hours of use and promoting healthier viewing habits.
- 【WIDEN YOUR PERSPECTIVE】Our sleek minimal bezel design ensures undivided attention. The nearly bezel-free display seamlessly connects in a dual monitor arrangement, delivering an unobstructed view that lets you focus on more at once, completely distraction-free.
Troubleshoot header requests
- The request is rejected: Check for duplicate header names (including case differences), restricted headers, control characters, or values beyond the documented size limits.
- A subresource does not receive the cookie or header: Confirm that
include_headers_on_subrequestsis enabled and that the resource’s exact origin is the requested origin or appears inadditional_header_origins. - A redirect or third-party resource does not receive the header: Header delivery is origin-scoped. Verify the scheme, host, and port and add only an authorized origin where needed.
- A sign-in page still asks you to log in: The API does not automate interactive login. Use an authorized session cookie or token, or an available embed.
- A form request parses a header incorrectly: Send each header as its own repeated
headers=name:valuefield; the first colon separates the name from the value.
Or skip the browser setup
ScreenshotNeo provides a one-request screenshot API. For example, this cURL request captures a URL as WebP:
Quick Recap
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpSee the ScreenshotNeo API documentation for the request options. Its captures remove cookie and consent banners, newsletter popups, and chat widgets before the shot; each cleanup step can be turned off. Bot checks, blank pages, failed loads, timeouts, and cache hits are not billed. It also has an MCP server with screenshot tools for AI agents. The free plan includes 1,000 screenshots a month with no card; paid plans start at $5 for 3,000. Learn about ScreenshotNeo, then sign up for 1,000 free screenshots a month with no card.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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