How do you migrate Visualforce pages to LWC at scale?

The migration is rarely a like-for-like rewrite — Visualforce and LWC have different paradigms. The strategy:

Inventory phase:

1. List every Visualforce page in the org (Setup -> Visualforce Pages).
2. Categorise: simple display pages, controller-heavy interactive pages, PDF generators, embedded utilities.
3. Identify which can be deprecated (replaced by Lightning Record Pages, Path, or out-of-the-box features) vs which need a real LWC equivalent.

Per-page rewrite:

1. Simplify scope. Visualforce pages often pile multiple features onto one page. Each LWC component should do one thing well.
2. Decompose — split the VF page into a parent LWC plus child components for distinct concerns (header, list, form, footer).
3. Replace controller logic:

• Standard controllers -> Lightning Data Service getRecord / updateRecord.
• Custom controllers -> @AuraEnabled Apex methods called via @wire or imperatively.
• Visualforce-specific tags (<apex:pageBlock>, <apex:dataTable>) -> Lightning Base Components (lightning-card, lightning-datatable).

1. Replace remoting and AJAX -> async/await on imperative @AuraEnabled calls.
2. Replace ViewState — LWC has no ViewState. State lives on the client; you store in component reactive properties.
3. Replace inline styles -> SLDS classes or scoped CSS.
4. Test in Lightning Experience — VF pages worked in Classic; LWC is Lightning-only.

Deployment strategy:

• Run side-by-side — keep VF page live while LWC is built and tested.
• Use the App Builder to swap which page renders for users. Switch a profile at a time.
• Telemetry — log usage of the VF page; deprecate when usage drops.

What can't easily migrate:

• VF Email Templates — keep these on VF; new templates can be Lightning Email Templates but old ones don't auto-convert.
• PDF rendering (renderAs="pdf") — no direct LWC equivalent. Keep VF or use external PDF services.
• VF embedded in legacy custom buttons — depends on the button.

Tooling:

• VS Code extensions for editing both VF and LWC side by side.
• Salesforce Migration Workbook (Salesforce documentation) — patterns for common VF -> LWC translations.

Migration is multi-quarter for VF-heavy orgs. Phase by user impact: rewrite high-traffic pages first.