Every step below is from an official source
Switch from 1Password to Bitwarden
What to do at 1Password before you leave, what Bitwarden needs when you join, and everything else the switch touches. Your full plan is built in your browser and stays there.
Official sources reviewed . How we review sources
At 1Password, before you leave
Export from the 1Password desktop appBefore
On a Mac, open and unlock 1Password, select File > Export and choose the account. Pick 1PUX or CSV, then select Export Data.
How to export your data from the 1Password apps1Password Support. ReviewedExport passkeys from the iOS or Android appBefore
1Password says passkeys can only be exported in 1Password for iOS and Android at this time.
How to export your data from the 1Password apps1Password Support. ReviewedKnow what a CSV export leaves outBefore
A CSV export does not include security questions, linked items, linked apps or custom fields.
How to export your data from the 1Password apps1Password Support. ReviewedDelete the plaintext export file when doneAfter
Exported files are not encrypted and are stored in plaintext. Don't email them or store them online, and delete them when you are done.
How to export your data from the 1Password apps1Password Support. Reviewed
At Bitwarden, when you join
Import from LastPass, 1Password, Chrome and moreDuring
Bitwarden supports imports from common password managers, including LastPass, 1Password, Firefox, Chrome, Edge, Chromium, Password Safe and other Bitwarden vaults.
Import to your vault or collectionsBitwarden Help Center. ReviewedImport LastPass directly, then add attachments by handDuring
Bitwarden's browser extensions and desktop apps can import your individual LastPass vault directly, with no file upload. File attachments and trash must be uploaded to your vault by hand.
Import from LastPassBitwarden. ReviewedSplit files with more than 40,000 itemsBefore
An imported file can contain up to 40,000 items. If your file is too large, split it into smaller files and import each one.
Import to your vault or collectionsBitwarden Help Center. ReviewedDelete the export file after importingAfter
Once your data is in Bitwarden, delete the exported data file from your computer.
Import to your vault or collectionsBitwarden Help Center. Reviewed
Then: everything else the switch affects
The steps above are what 1Password and Bitwarden say. Your full checklist adds the accounts, codes, payments and devices that depend on your password manager, in a safe order. It's built from your answers, in your browser.