How to convert images to WebP in bulk, from a list of URLs

Updated 2026-11-10 · Data and API builders · by CyberMax

Copy-paste code

Python (pip install apify-client): image URLs in, WebP ZIP out

Copyimport os
from apify_client import ApifyClient

client = ApifyClient(os.environ["APIFY_TOKEN"])
urls = [line.strip() for line in open("images.txt") if line.strip()]
run = client.actor("cybermax/image-converter").call(run_input={
    "images": urls,
    "format": "webp",        # or "avif", "jpeg", "png", "original"
    "quality": 80,
    "maxWidth": 1600,
    "output": "zip",
})
for r in client.dataset(run["defaultDatasetId"]).iterate_items():
    print(r["status"], r.get("fileName"), r.get("inputBytes"), "->", r.get("outputBytes"), r.get("savedPercent"))
out = client.key_value_store(run["defaultKeyValueStoreId"]).get_record("OUTPUT")
print(out["value"])  # totals and the ZIP link(s)

Python: every image from a website, then WebP (Picpail -> Pixkiln)

Copy# 1) list every image on the pages (Picpail, $0.0008 per image found)
pics = client.actor("cybermax/bulk-image-downloader").call(run_input={
    "urls": ["https://www.example-store.com/collections/all"],
    "output": "list", "minWidth": 300,
})
# 2) convert that dataset to WebP, max 1200 px
webp = client.actor("cybermax/image-converter").call(run_input={
    "datasetId": pics["defaultDatasetId"], "format": "webp", "maxWidth": 1200,
})

JavaScript / Node (npm i apify-client)

Copyimport { ApifyClient } from 'apify-client';

const client = new ApifyClient({ token: process.env.APIFY_TOKEN });
const run = await client.actor('cybermax/image-converter').call({
  images: ['https://www.gstatic.com/webp/gallery/1.jpg'],
  format: 'webp', quality: 80, maxWidth: 1600,
});
const { items } = await client.dataset(run.defaultDatasetId).listItems();
for (const r of items) console.log(r.fileName, r.inputBytes, '->', r.outputBytes, `${r.savedPercent}%`);

No code: n8n, Make or Zapier

Copyn8n: HTTP Request node (or the Apify node, action "Run an Actor and get dataset")
Method:  POST
URL:     https://api.apify.com/v2/acts/cybermax~image-converter/run-sync-get-dataset-items
Auth:    Header Auth  ->  Authorization: Bearer <your Apify token>
Body:    JSON  {"images": {{ $json.imageUrls }}, "format": "webp", "maxWidth": 1600}
Output:  one n8n item per result row

Make:    Apify app -> "Run an Actor" (Actor: cybermax/image-converter, wait for finish = yes)
         -> Apify "Get Dataset Items" (dataset = the run's defaultDatasetId) -> your next module
Zapier:  Apify app -> action "Run Actor" (cybermax/image-converter, input JSON as above)
         -> trigger "Finished Actor Run" -> "Fetch Dataset Items" -> your app
Runs longer than 5 minutes: start with POST /v2/acts/cybermax~image-converter/runs and read the dataset when the run finishes.

Store flow: a weekly Apify Schedule runs Picpail on your catalogue, then Pixkiln on its dataset, so a WebP copy of every product photo stays current.

From an AI agent (MCP)

Copy# Any MCP client (Claude Desktop, Claude Code, Cursor, VS Code): Apify's hosted MCP server
{
  "mcpServers": {
    "image-converter": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://mcp.apify.com/?tools=cybermax/image-converter",
               "--header", "Authorization: Bearer ${APIFY_TOKEN}"],
      "env": { "APIFY_TOKEN": "<your Apify token>" }
    }
  }
}
# The agent sees one tool, cybermax--image-converter, with the Actor's input schema.
# Ask: "convert these 40 product photos to WebP, max 1200 px wide".

Source: Pixkiln (Apify Actor cybermax/image-converter) README, real Apify run on 10 Nov 2026; the same 60 large photos as AVIF at max 1200 px went from 46.9 MB to 0.9 MB

WebP or AVIF?

WebP is the safe default: every current browser shows it, and Shopify, WooCommerce and WordPress accept WebP uploads. Photos usually end up 25-35% smaller than a good JPEG at the same visual quality.

AVIF is smaller still (often half of WebP) but slower to encode and not shown by some older Safari versions. Use it for a CDN that can fall back to WebP, or when page weight matters more than reach.

Bulk image converter for Shopify, WooCommerce and Core Web Vitals

Large images are the most common reason for a slow Largest Contentful Paint. Converting product photos to WebP at the width they are actually shown at cuts page weight without a visible change, and stripping EXIF removes camera and GPS data you did not mean to publish.

Pixkiln never enlarges a small image unless you ask, applies the photo's orientation before stripping metadata (nothing comes out sideways), puts transparent PNGs onto white when you convert to JPEG and keeps every frame of an animated GIF as animated WebP.

Download every image first, then convert

Picpail finds every image on a list of pages at full size (srcset, lazy-loaded and CSS background images included). Run it in "list" mode and give its dataset ID to Pixkiln: you get one ZIP of web-ready images without handling a single file.

Good to know

Price on Apify: $0.0015 per image converted ($1.50 per 1,000), whatever the image size, no start fee. Failed downloads, unreadable files and files over your size limit are free. Apify's free plan includes $5 of usage each month (about 3,300 images).

Pixkiln only downloads public URLs and changes size, format and compression; it does not remove backgrounds or add watermarks.

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