two-way-sync-between-apps

Use it when

• People create or edit the same records in both apps.
• Edits must reach the other app within seconds to 24 hours; the sync's Data Sync Frequency goes from 0 seconds of added wait to every 24 hours.
• The records match one to one between the two tables.

Why this design

Advantages:

• One sync replaces two one-way integrations that would overwrite each other.
• Direction is set per table pair, so one sync can hold two-way and one-way tables.
• Read-only fields (record ids, formula fields, last modified times) sync only out of their app.
• A per-app rate limit keeps the sync under each app's API limit.

Trade-offs:

• Records already in both apps are not merged: a contact in both before the first run ends up twice in each. Start with one side empty, or remove the overlap first.
• A delete in one app deletes the record in the other unless Delete Protection is on.