Image watermark API
for developers

Manual watermarking works for a handful of images, but it does not scale. If you are building a platform that handles user uploads, running an e-commerce store with product photos, or managing a photography portfolio with hundreds of images, you need automation. An image watermark API lets you add watermarks as part of your existing pipeline - no manual steps, no desktop software, no human bottleneck.

With the Markly API, watermarking becomes a single HTTP call. Upload an image, specify your watermark settings, and get the result back in seconds. It fits into CI/CD pipelines, CMS hooks, mobile app backends, and batch scripts alike. Combined with a solid photo protection strategy, API-driven watermarking is the most reliable way to protect visual content at scale.

The Markly API is a REST API that accepts multipart form data. You send an image along with watermark parameters, and get back the watermarked image. Authentication uses API keys passed in the Authorization header.

The API provides four main endpoints:

All endpoints accept JPEG, PNG, and WebP images up to 25 MB. Responses return the processed image directly in the same format, or a ZIP for batch requests.

Here are working examples for the most common languages. Replace YOUR_API_KEY with your actual key from the developer dashboard.

curl -X POST https://www.markly.cloud/api/v1/watermark/text \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "[email protected]" \
  -F "text=© 2026 My Brand" \
  -F "font_size=24" \
  -F "opacity=0.5" \
  -F "position=bottom-right" \
  -o watermarked.jpg

import requests

response = requests.post(
    "https://www.markly.cloud/api/v1/watermark/text",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    files={"image": open("photo.jpg", "rb")},
    data={
        "text": "© 2026 My Brand",
        "font_size": 24,
        "opacity": 0.5,
        "position": "bottom-right",
    },
)

with open("watermarked.jpg", "wb") as f:
    f.write(response.content)

import fs from "fs";
import FormData from "form-data";
import axios from "axios";

const form = new FormData();
form.append("image", fs.createReadStream("photo.jpg"));
form.append("text", "© 2026 My Brand");
form.append("font_size", "24");
form.append("opacity", "0.5");
form.append("position", "bottom-right");

const res = await axios.post(
  "https://www.markly.cloud/api/v1/watermark/text",
  form,
  { headers: { Authorization: "Bearer YOUR_API_KEY", ...form.getHeaders() },
    responseType: "arraybuffer" }
);

fs.writeFileSync("watermarked.jpg", res.data);

The API is available on every Markly plan, including the free tier. Usage is measured in credits - one credit per image processed (text or logo). Batch requests consume one credit per image in the batch.

All paid plans include the logo watermark endpoint, batch processing, and usage analytics. Unused credits on subscription plans roll over for one month. Rate limits are per API key, not per IP.

Markly also provides a Model Context Protocol (MCP) server that lets AI assistants and agents watermark images on your behalf. If you use tools like Claude, Cursor, or custom LLM agents, the MCP server exposes the same watermarking capabilities through a standardized tool interface.

The MCP server supports text watermarks, logo watermarks, and batch processing - the same features available through the REST API. See the developer documentation for setup instructions and the MCP configuration JSON.

You can start using the watermark API in three steps:

Full endpoint reference, parameter documentation, and error codes are available in the developer documentation.