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# Sync customers or suppliers

> How to bidirectionally sync customer and supplier contacts with accounting platforms using the Merge Accounting API.

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#### User authorizes access

Your user authorizes your application to access their accounting service (e.g., QuickBooks Online, NetSuite) via an OAuth or similar authorization flow through Merge Link.

#### Fetch contacts

Utilize the [**GET** /contacts](https://docs.merge.dev/accounting/contacts/#contacts_list) endpoint to fetch the customers/suppliers from your customer's accounting system.

#### Reconcile contacts

Match any customers/suppliers that already exist in your backend through identifiers like `name`, `email_address`, `tax_number`, `address`, and `phone_number`. If any customers/suppliers cannot be matched automatically, surface a matching UI to your user.

#### Create contacts

Utilize the [**POST** /contacts](https://docs.merge.dev/accounting/contacts/#contacts_create) endpoint to create any customers/suppliers that exist in your platform, but not your customer's accounting system.

#### Refresh data regularly

After the initial reconciliation of customers/suppliers, regularly call the [**GET** /Contacts](https://docs.merge.dev/accounting/contacts/#contacts_list) endpoint using the `modified_after` query parameter to track updates to contacts, as well as new contacts to keep your tables up to date.

Now your customers can automatically have the most up-to-date list of suppliers or customers in their accounting platform and your product.

> **Note**
>
> Webhooks can be utilized to make this process more efficient.

#### Sync your users

Integrate today or talk to our sales team to learn how Merge unlocks hundreds of integrations in days - not years.

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Get a demo **

* [Webhooks](/merge-unified/reading-data/webhooks/merge-webhooks)

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