The Complete On-Page SEO Audit Checklist for Developers

The Developer's SEO Checklist

Search engine optimisation often sits between marketing and engineering. This checklist focuses on the technical elements developers control directly.

Title and Meta Tags

<title>Descriptive Page Title — Brand Name</title>
<meta name="description" content="150–160 character description that appears in SERPs.">

• Title: 50–60 characters, unique per page, primary keyword near the start
• Meta description: 150–160 characters, compelling call to action
• No duplicate titles or descriptions across pages

Heading Hierarchy

One <h1> per page, containing the primary keyword. <h2>–<h6> form a logical outline. Don't skip levels.

Image Optimisation

<img src="product.webp" alt="Blue widget model XB-300 in packaging" width="800" height="600">

• alt text describes the image content meaningfully
• width and height attributes prevent layout shift (CLS)
• Use WebP or AVIF formats

Canonical URLs

<link rel="canonical" href="https://example.com/products/widget/">

Prevents duplicate content penalties when the same page is accessible at multiple URLs.

API Audit

curl -X POST https://api.toolkitapi.io/v1/seo/audit \
  -H "X-API-Key: $API_KEY" \
  -d '{"url": "https://example.com/product/"}'

{
  "score": 78,
  "issues": [
    { "type": "missing_meta_description", "severity": "high" },
    { "type": "images_without_alt",       "count": 3, "severity": "medium" },
    { "type": "title_too_long",           "length": 72, "severity": "low" }
  ]
}

Automated Pre-Deploy Check

Add an SEO audit to your deployment pipeline to catch regressions before they go live. Set a minimum score threshold and fail the build if it's not met.