# How to Migrate Your CIAM Platform Without Downtime

Source: https://startwithidentity.com/articles/ciam-migration-guide/
Last updated: 2026-07-16
License: content by Start with Identity. Cite the source URL.

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Replatforming customer identity is one of the higher-risk projects an engineering team takes on, because the failure mode is locking real customers out of their accounts. Done carefully, a [CIAM](https://startwithidentity.com/guides/fundamentals/what-is-ciam/) migration is invisible to users. Done as a big-bang cutover with a forced password reset, it becomes a support crisis and a measurable loss of active accounts. This guide is the careful version.

## Why teams migrate

The usual triggers are a platform that no longer meets security expectations, pricing that scales badly with growth, missing capabilities such as passkeys or enterprise federation, or an end-of-life announcement. Whatever the reason, the goal is the same: move the users without the users noticing. Where the intent is specifically moving off an older platform, keep the evaluation vendor-neutral; the [LoginRadius versus Auth0 comparison](https://startwithidentity.com/compare/loginradius-vs-auth0/) is one worked example of that decision, and the [best CIAM platforms](https://startwithidentity.com/rankings/best-ciam-platforms/) ranking covers the current field.

## Choose a migration model

**Bulk migration.** Export all users from the old platform and import them into the new one before cutover. It is clean and fast to reason about, and it works when you can export the data you need, including password hashes. The risk is that anything wrong in the mapping affects everyone at once.

**Lazy (just-in-time) migration.** Migrate each user at their next login. The new platform verifies the credential against the old system once, then stores it locally. Dormant accounts are never re-hashed until they return. It spreads risk across weeks but requires both systems to run in parallel.

Most real migrations combine the two: bulk-import the profile data and importable hashes, then use lazy verification for anything that could not be moved cleanly.

## The password problem

The single biggest question is whether you can move passwords. If the old platform stores them with a standard algorithm (bcrypt, scrypt, Argon2, or PBKDF2), a modern platform can usually import the hashes as-is, and customers never notice. If the hashes are proprietary or unreachable, lazy migration is the escape hatch: validate against the old system at login, then re-hash into the new one. The outcome to avoid is a forced reset email to your entire base, which always loses a chunk of active users. Treat a migration as the moment to also offer [passwordless and passkeys](https://startwithidentity.com/articles/passwordless-ciam-guide/), so returning users can adopt a stronger method instead of re-entering an old one.

## A phased cutover

1. **Assess and map.** Inventory user attributes, custom fields, roles, connected applications, and every integration that calls the identity API. Map each to the new platform. Decide what to drop.
2. **Parallel run.** Stand up the new platform alongside the old. Sync or bulk-load data. Keep the old system authoritative.
3. **Pilot cohort.** Route a small percentage of logins to the new platform. Watch login success rate, error types, and support tickets. Fix, repeat.
4. **Staged cutover.** Widen the cohort in steps. Keep rollback available at each step, so a bad cohort reverts without touching the rest.
5. **Decommission.** Once traffic is fully on the new platform and a full billing or renewal cycle has passed cleanly, retire the old system and its data per your retention policy.

## What to monitor

Login success rate is the vital sign; a dip means real users are being turned away. Watch password-reset volume (a spike means migration is not transparent), support ticket categories, and token or session errors on connected applications. Instrument these before you move the first cohort, not after.

## Plan the rollback first

Every phase needs an answer to "what if this cohort fails?" That means the old platform stays live and authoritative until a cohort is verified, data written to the new system during parallel run can be reconciled, and you have decided in advance the login-success threshold that triggers a revert. A migration without a rollback plan is a bet that nothing will go wrong, and something always does.

Use the [how to evaluate CIAM](https://startwithidentity.com/guides/buyer-guides/how-to-evaluate-ciam/) guide to pick the destination platform, and confirm during evaluation that it supports hashed-password import and a documented migration path, because that single capability decides how smooth the move will be.