How to test your website after every deployment
Every deployment is a small bet that nothing you didn't touch also changed. Most of the time it pays off. But the failures are quiet: a contact form that no longer submits, a checkout step that 500s on mobile, a layout that breaks at one breakpoint. Nobody notices until a customer does. Here's how to catch those regressions first.
What can break after a deployment
A deployment touches code, config, content, or all three. Any of these can cascade:
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Forms
Submissions silently fail, validation breaks, confirmation messages never fire, or data lands in the wrong place.
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Critical journeys
Signup, checkout, and booking flows break a step in — often silently, often only on certain browsers or viewport sizes.
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Links
Internal and external links 404 after a content migration, URL slug change, or CMS restructure.
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Visual / layout
CSS changes shift or break the layout at certain breakpoints. A visual regression that doesn't break functionality but harms the experience.
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Performance
A new script, unoptimised image, or third-party embed tanks load time — affecting Core Web Vitals and user experience.
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Third-party scripts
Analytics, chat widgets, or payment embeds stop loading due to CSP changes, domain updates, or dependency conflicts.
The manual post-deployment checklist
Run through this after every deployment. It won't catch everything, but it catches the most common regressions before your users do.
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1
Load key pages
Open the homepage, main landing pages, and any pages touched in this deployment. Check for layout breaks, missing images, and errors in the browser console.
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2
Submit every form
Test each form — contact, newsletter, lead capture, checkout. Confirm submissions succeed, confirmation messages appear, and data lands correctly.
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3
Walk every critical journey
Manually complete signup, checkout, booking, or any other high-value flow end to end — on both desktop and mobile viewport.
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4
Check navigation and internal links
Click through the main navigation and links in any recently changed content. Look for 404s, broken anchors, and redirect loops.
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5
Compare against a known-good snapshot
Compare the current state of key pages against a pre-deployment screenshot. Look for unintended layout shifts, colour changes, or missing elements — visual regressions that don't break functionality.
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6
Verify analytics and third-party scripts
Confirm tracking fires on key events. Check that chat, payment widgets, and other embeds still load and function correctly.
Why manual testing doesn't scale
A thorough manual pass takes 30–60 minutes per release and depends on someone remembering every critical path. It doesn't run at night or on every PR, and it gets skipped under deadline pressure. That's exactly when regressions ship.
The checklist above is the right foundation. Running it manually when your team ships frequently means choosing between slower releases or accepted risk. Neither works long-term.
30–60
minutes per manual pass
0
runs at night or on PRs
100%
dependent on someone remembering
Automating it: regression + visual + monitoring
The goal: run that checklist on every deploy without anyone initiating it. In practice, that means three things:
Automated checks that forms submit, journeys complete, and links resolve — run automatically after every deployment.
Automated screenshot comparison that detects layout shifts, style changes, and missing elements against a known-good baseline.
Ongoing checks that run between deployments too — because regressions can appear from third-party changes, CDN issues, or infrastructure drift, not just your own deployments.
How Mira does this automatically
Mira learns your site's pages and critical journeys, then re-runs the whole checklist automatically after every change: submitting forms, walking journeys, comparing against the last known-good state for visual regressions. It runs continuously rather than on request, and it's hosted in Europe with GDPR-compliant infrastructure.
See also: the best AI website testing tools in 2026 · GDPR-compliant website testing
Frequently asked questions
- What is website regression testing?
- Website regression testing is the process of verifying that a change to your website hasn't broken something that was previously working. It covers functional regressions (forms, journeys, links) and visual regressions (layout, styling).
- How is visual regression testing different from functional testing?
- Functional testing checks whether things work — a form submits, a page loads, a journey completes. Visual regression testing compares screenshots to catch unintended visual changes — layout shifts, colour changes, missing elements — that don't break functionality but harm the experience.
- Can I automate post-deployment testing without writing code?
- Yes. Mira Checks learns your website and runs the entire post-deployment checklist automatically — submitting forms, walking journeys, and comparing against the last known-good state for visual regressions. No scripts, no recordings, no code.
Want this checklist to run itself after every deploy?
Get early access to Mira — autonomous website QA that runs the whole post-deployment checklist without you lifting a finger.