The accepted answer is related to PgAdmin 3 which is outdated and not supported.
For PgAdmin 4 and above, the application is running in the browser.
After you create your table, you have to make sure that your table has a primary key otherwise you couldn’t edit the data as mentioned in the official documentation.
To modify the content of a table, each row in the table must be
uniquely identifiable. If the table definition does not include an OID
or a primary key, the displayed data is read only. Note that views
cannot be edited; updatable views (using rules) are not supported.
1- Add primary key
Expand your table properties by clicking on it in the pgAdmin4 legend. Right-click on ‘Constraints’, select ‘Create’ –> ‘Primary Key’to define a primary key column.
2- View the data in excel like format
Browser view, right-click on your table –> select View/Edit Data –> All Rows
3- Add new row / Edit data
On the Data Output tab at the bottom of the table below the last row, there will be an empty row where you can enter new data in an excel-like manner. If you want to make updates you can also double click on any cell and change its value.
4- Save the changes
Click on the ‘Save’ button on the menu bar near the top of the data window.
