After you finalize your data schema above, you may start sending your data into Unit21’s sandbox. To send data, you have a few options:
## APIs
You may use these Unit21 APIs to get data into the sandbox.
* [Create Entity](https://docs.unit21.ai/u21/reference/create_entity)
* [Create Instrument](https://docs.unit21.ai/u21/reference/create_instrument)
* [Create Event](https://docs.unit21.ai/u21/reference/create_event)
* [Create Device](https://docs.unit21.ai/u21/reference/create_device)
## JSON file
You may use the following methods to upload JSON files.
* You may [drag & drop a JSON file](https://docs.unit21.ai/u21/docs/datafile-uploads) on Unit21’s user interface
* You may set up an API to [batch upload the file](https://docs.unit21.ai/u21/reference/batch-request-examples#batch-case-requests)
### Note: see [Best Practices](doc:best-practices) when sending data into the system.
After you have loaded data, log onto the user interface and validate your entities, instruments and transactions.
* On the left navigation, go **Data Explorer** > **Entities** > click on an entity and see if there are values in the fields that are defined in the entity data schema sheet
* **Data Explorer** > **Instruments** >> click on an instrument and see if there are values in the fields that are defined in the entity data schema sheet
* **Data Explorer** > **Transactions** >> click on an transaction and see if there are values in the fields that are defined in the entity data schema sheet
Your Unit21 Implementation Manager will also set up a session to review your data with you and compare the data on your UI against your data schema document. The goal is to see uniformity between the UI and the data schema. If it is, then you can sign off the data pipeline before moving to production.