Open Source ESRGAN API

A production open source ESRGAN API that enlarges any photo 4× to 16× and returns a full-resolution PNG. One HTTP POST. No software to install. $0.009 per image — lower-priced than Let's Enhance ($0.068) and Upscale.media (~$0.052). 5,000 free credits (24-hour trial), no credit card.

Quick start — open source ESRGAN API in one call

Sign up, copy your key from the dashboard, and POST your image. The endpoint queues the job and returns a generation_id; poll GET /v1/image/upscale/{id} until status=completed, then download the full-resolution PNG from output_url.

curl -X POST https://api.pixelapi.dev/v1/image/upscale \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "[email protected]" \
  -F "scale=4"
# Response: {"id": "uuid", "status": "queued", "credits_used": 9}

# Poll until completed
curl https://api.pixelapi.dev/v1/image/upscale/UUID \
  -H "Authorization: Bearer YOUR_API_KEY"
# Response: {"generation_id": "uuid", "status": "completed", "output_url": "https://..."}

pip install pixelapi
---
from pixelapi import PixelAPI

client = PixelAPI(api_key="YOUR_API_KEY")
result = client.upscale(image="photo.jpg", scale=4)
result.save("photo_4x.png")  # full-resolution PNG

npm install pixelapi
---
import { PixelAPI } from "pixelapi";

const client = new PixelAPI({ apiKey: process.env.PIXELAPI_KEY });
const result = await client.upscale({ image: "./photo.jpg", scale: 4 });
await result.save("photo_4x.png");  // full-resolution PNG

composer require pixelapi/pixelapi
---
<?php
use PixelAPI\Client;

$client = new Client(getenv("PIXELAPI_KEY"));
$result = $client->upscale(["image" => "photo.jpg", "scale" => 4]);
file_put_contents("photo_4x.png", $result->getBody());

gem install pixelapi
---
require "pixelapi"

client = PixelAPI::Client.new(api_key: ENV["PIXELAPI_KEY"])
result = client.upscale(image: "photo.jpg", scale: 4)
File.binwrite("photo_4x.png", result.body)

go get github.com/pixelapi/pixelapi-go
---
import "github.com/pixelapi/pixelapi-go"

client := pixelapi.New("YOUR_API_KEY")
result, err := client.Upscale("photo.jpg", pixelapi.UpscaleOptions{Scale: 4})
if err != nil { panic(err) }
result.Save("photo_4x.png")

Pricing — open source ESRGAN API vs rivals

PixelAPI's per-image price is set at half or below the cheapest comparable REST API rival. No annual commitment. No subscription required for pay-per-image access.

Pricing verified from each rival's public pricing page October 2026. PixelAPI per-image price follows our pricing principle: half or below the cheapest comparable REST API rival per-unit rate.

What you get back

Common workflows using the ESRGAN API

The open source ESRGAN API is the resolution layer in these production pipelines. Each links to a setup guide:

More use-case guides: all upscaling workflows →

Integrations & SDKs

Comparison vs alternatives

Rate limits & error handling

20 requests/minute on the free trial, 60 on Starter, 120 on Pro and 300 on Scale, plus 3/10/20/50 concurrent jobs in parallel respectively (see parallel processing docs). Exceeding the limit returns HTTP 429 with a Retry-After header. Recommended: exponential backoff starting at 2 s, doubling on each retry up to 30 s. The Python and Node SDKs handle this automatically.

# Python SDK — auto-retries 429 with exponential backoff
from pixelapi import PixelAPI
client = PixelAPI(api_key="...", max_retries=4)
result = client.upscale(image="photo.jpg", scale=4)  # auto-retries on 429

Failed jobs trigger an automatic, idempotent credit refund — you never pay for a broken result. You can safely retry the same generation_id via the poll endpoint; the refund logic prevents double-credit regardless of how many times you check.

Input limits: max 20 MB per image. Scale values outside 2–16 return HTTP 400. target_width and target_height must be supplied together (64–16,384 px each); supplying only one returns HTTP 400. Unsupported fit_mode values also return HTTP 400 with a descriptive message.

Frequently asked questions