CompleteArchitecture

Vue 2 → Vue 3 Migration

Planned and executed a 9-month zero-downtime migration from Vue 2 + Options API to Vue 3 + Composition API for a 300+ component library serving 1M+ users.

CompanyZoho

RoleTech Lead

Year2022

Tech Stack

Vue 3ViteVitestPlaywrightStorybookESLint

Impact

components300+ components

users1M+ users

downtimeZero downtime

The Problem

Vue 2 reached end-of-life and the 300+ component library had no migration path. With 1M+ daily users, any downtime was unacceptable.

The Solution

Designed a strangler fig migration strategy using vue-demi for compatibility, automated codemods for Options API → Composition API conversion, and parallel test suites.

Architecture

Gradual migration with vue-demi bridge layer, automated codemods for ~60% of migrations, and feature flags to control rollout.

Key Challenges

Maintaining backward compatibility during migration
Migrating complex Options API patterns to Composition API
Keeping 300+ Storybook stories functional throughout

Results & Impact

All 300+ components migrated

0 minutes of downtime

1M+ users unaffected

Test coverage increased from 34% to 89%