Thum.io Alternatives: The Best Screenshot API to Replace image.thum.io (2026)

The best thum.io alternative is a dedicated screenshot API — ScreenshotAPI — that returns finished PNG, JPEG, WebP, or PDF bytes from a single authenticated GET request, with full-page capture, dark mode, and ad/cookie-banner blocking on every plan and a free tier of 200 screenshots per month (no credit card). image.thum.io is excellent for zero-setup <img>-tag thumbnails on its free 1,000-impressions/month tier, but it renders at a fixed 1200×1200 viewport, gates full-page capture behind paid plans, and streams an animated placeholder while an un-cached URL renders — so for production screenshots you usually want a purpose-built API.

If you found this page, you are probably already using image.thum.io/get/... in an <img> tag and have hit one of its edges: you need a full-page capture without upgrading, a PDF, a specific viewport size, or a guarantee that the response is the real screenshot and not the loading placeholder. This guide explains exactly how thum.io works today, where it stops, and how to move the same capture to a dedicated API with one line of code.

How image.thum.io works

thum.io is a website-screenshot service you call by URL — there is no SDK and, on the free tier, no API key. You embed the target URL directly in an image tag (facts below verified against thum.io, 2026-07-21):

html
<!-- Basic thum.io capture -->
<img src="//image.thum.io/get/https://example.com/" />

<!-- With documented modifiers: width and crop -->
<img src="//image.thum.io/get/width/1200/crop/900/https://example.com/" />

Key facts about the service today:

• Free tier: up to 1,000 impressions per month, no signup required.
• Documented modifiers: width/[pixels], crop/[pixels], and maxAge/[value] for cache control. Adjustable viewport width and full-page capture are unlocked on paid/advanced plans.
• Render size: captures are taken from a 1200×1200 pixel browser.
• First-render behavior: for an un-cached URL, the service streams an animated placeholder GIF while the capture renders, then serves the real image once ready.
• Auth: paid usage is authenticated with signed requests (custom expiry) or by referer.
• Pricing: Good — $2 per 10,000 hits ($1/month minimum); Better — $1 per 10,000 hits ($20/month minimum); Enterprise — custom.

For embedding a quick thumbnail of a URL in a directory or a link card, this is genuinely hard to beat — it is one line of HTML and costs nothing to start.

Where developers outgrow thum.io

The same design choices that make thum.io simple become limits when screenshots become a real feature of your product:

1. Full-page capture requires a paid plan. The single most common thum.io query is developers looking for a full-page screenshot — but on thum.io that is a paid/advanced-plan feature, not a free-tier flag.
2. The animated-placeholder response. Because the first request for an un-cached URL returns a streaming placeholder, a server-side fetch() can save the loading GIF instead of the finished screenshot unless you add retry logic. That is a subtle, hard-to-debug failure in an automated pipeline.
3. Fixed 1200×1200 render. You cannot freely set an arbitrary viewport (e.g. a 375px-wide mobile capture or a tall 1440×2000 marketing shot) on the free tier.
4. No PDF, dark mode, or ad/cookie-banner blocking. thum.io is a thumbnail service; it does not offer document (PDF) output, forced dark-mode capture, or automatic removal of ads and cookie consent dialogs.
5. Per-referer / signed-URL auth model. For a backend pipeline you generally want a straightforward secret API key in a header, not referer-based access or per-request URL signing.

None of these make thum.io "bad" — they make it a thumbnail widget rather than a production screenshot API. When you need the second thing, switch.

image.thum.io vs ScreenshotAPI

(thum.io feature set and pricing per thum.io, verified 2026-07-21; ScreenshotAPI capabilities per the Screenshot API reference.)

Move a thum.io capture to ScreenshotAPI in one line

The mental model is almost identical — a URL with options — except you send an API key in a header and you get the finished image bytes back directly.

A basic thumbnail (thum.io on the left, ScreenshotAPI on the right):

bash
# thum.io
//image.thum.io/get/width/1200/https://example.com

# ScreenshotAPI
curl "https://screenshotapi.to/api/v1/screenshot?url=https://example.com&width=1200" \
  -H "x-api-key: sk_live_xxxxx" \
  --output screenshot.png

The full-page capture that thum.io reserves for paid plans is a single flag here:

bash
curl "https://screenshotapi.to/api/v1/screenshot?url=https://example.com&fullPage=true" \
  -H "x-api-key: sk_live_xxxxx" \
  --output fullpage.png

In JavaScript, you get deterministic image bytes — no placeholder to retry around:

javascript
const response = await fetch(
  'https://screenshotapi.to/api/v1/screenshot?url=https://example.com&fullPage=true&type=png',
  { headers: { 'x-api-key': 'sk_live_xxxxx' } }
);
const image = Buffer.from(await response.arrayBuffer());
// `image` is the final screenshot — write it to disk, S3/R2, or return it directly.

Need a PDF for an invoice or archive, or a dark-mode capture? Add type=pdf or colorScheme=dark. Capturing a site buried under ads or a cookie wall? Add blockAds=true&removeCookieBanners=true. All of these are query parameters on the same endpoint — see the full Screenshot API reference.

200 free screenshots per month — no credit card required. Credit packs are also available for one-time purchases:

When image.thum.io is still the right call

Stay on thum.io if your use case is exactly what it is built for:

• You only need a small embeddable thumbnail of a URL in an <img> tag.
• 1,000 free impressions per month is enough and you want zero setup — no key, no account.
• A fixed 1200×1200 render and PNG/JPG output cover your needs.
• You do not need PDF, dark mode, custom viewports, or a guaranteed-final response.

For directory thumbnails and link previews specifically, that is often plenty — and if you are building exactly those, see website thumbnails for directories and the link preview generator API for the patterns.

Bottom line

image.thum.io is a great one-line thumbnail widget with a genuinely useful free tier. The moment screenshots become a real feature — full-page captures, PDFs, custom viewports, dark mode, or simply a response you can trust in an automated job — a dedicated screenshot API is the better tool. ScreenshotAPI gives you all of that from the same URL-with-options mental model, with a free tier of 200 screenshots per month and no credit card required.

Start free with 200 screenshots per month →