[GTM glossary](/glossary.md) Bi-directional sync Data & Enrichment # Bi-directional sync Also known as: two-way sync In short Bi-directional sync, also called two-way sync, is an integration in which changes made in either of two connected systems are copied to the other. If a rep edits a phone number in the CRM, it updates the connected tool, and the reverse is also true. It contrasts with one-way sync, where one system is the source and the other only receives data. Two-way sync is convenient but needs clear rules, because both sides can change the same field. ## How it works The integration watches both systems for changes and applies each change to the other side, usually on a schedule or through event triggers. * **Field mapping:** Each field in one system is paired with a field in the other. * **Change detection:** The sync tracks what changed since the last run, often by timestamp. * **Conflict rules:** If both sides changed the same field, a rule decides which value wins. --- ## Where GTM teams use it * **CRM and marketing automation:** Lead status, owner, and lifecycle stage stay aligned between both tools. * **CRM and sales engagement:** Activity and sequence status flow back to the CRM while contact updates flow out. * **CRM and data tools:** Enriched fields flow in while reps corrections flow out. --- ## Conflict handling ### Pick a winner per field Decide for each field which system is the source of truth. For example, the CRM owns deal stage, while the marketing tool owns email subscription status. ### Use timestamps carefully A "last write wins" rule is simple but can overwrite good data with a stale edit. Use it only for low-risk fields. --- ## Common mistakes * **Syncing every field:** Sync only fields both teams need. More fields means more conflicts. * **No source of truth:** Without ownership rules, values flip back and forth. * **Duplicate creation:** Poor matching can create duplicate records in both systems. * **No monitoring:** Sync errors are silent unless someone reviews the error log. --- ## Bi-directional sync FAQs **What is bi-directional sync?** Bi-directional sync is an integration that copies changes in both directions between two systems. An update made in either tool is passed to the other, so both hold the same values. It is also called two-way sync. **What is the difference between one-way and bi-directional sync?** In a one-way sync, one system is the source and the other only receives updates. In a bi-directional sync, both systems can send and receive changes, which is more flexible but requires conflict rules to prevent overwrites. **What happens when a bi-directional sync has a conflict?** A conflict occurs when both systems change the same field before the next sync. The integration applies a rule you set, such as a preferred source system or the most recent edit, and may log the conflict for review. **Is bi-directional sync always better than one-way sync?** No. Two-way sync adds risk of overwrites and duplicates. If one system clearly owns the data, a one-way sync is simpler and safer. Use two-way only for fields that genuinely need to be edited in both places. Share term --- ## More related phrases * [Native integration](/glossary/native-integration.md) * [Account hierarchy](/glossary/account-hierarchy.md) * [CRM enrichment](/glossary/crm-enrichment.md) ## Similar phrases * [Field mapping](/glossary/field-mapping.md) Field mapping defines which field in one system matches which field in another, so data syncs, imports, and integrations land in the right place with the right format. * [Reverse ETL](/glossary/reverse-etl.md) Reverse ETL copies cleaned, modeled data from a data warehouse back into operational tools such as a CRM, ad platform, or sales engagement tool so teams can act on it. * [System of record (SoR)](/glossary/system-of-record.md) A system of record is the application designated as the authoritative source for a specific type of data, such as accounts and opportunities in a CRM. * [CRM integration](/glossary/crm-integration.md) CRM integration connects your customer relationship management system with other tools, such as marketing automation, data providers, and sales engagement, so records and activity sync automatically between them. * [Single source of truth (SSOT)](/glossary/single-source-of-truth.md) A single source of truth is one agreed, authoritative place for a given piece of data, so every team works from the same numbers instead of conflicting copies.