Hey there! Great question—let’s cut through the confusion here clearly.

First, let’s break down what an API Key can and can’t do with Google Sheets:

• API Keys only support read access for publicly shared sheets: If your Google Sheet is set to "Anyone with the link can view", you can use an API Key to pull data from it via the Sheets API. But that’s the full extent of its capabilities—you can’t write, update, or delete any data with just an API Key.
• API Keys can’t access private sheets or perform write operations: This is because API Keys don’t authenticate a specific user or grant permission to modify data. They’re designed for simple, unauthenticated requests to public resources, not for actions that require user-specific permissions or data changes.

So if your goal is to write data to a Google Sheet (whether it’s private or public), or access a sheet that isn’t fully public, an API Key won’t cut it. You’ll need one of these alternatives:

• OAuth 2.0: The standard method for accessing user-owned sheets. It requires users to grant your app permission to access their sheets, which is necessary if you’re building an app that interacts with other people’s Google Sheets.
• Service Accounts: A better fit if you’re working with sheets owned by your organization, or if you want to avoid requiring user consent. You can create a service account in the Google Cloud Console, download its key file, then share your Google Sheet with the service account’s email address. Once set up, you can use the service account credentials to read and write to the sheet programmatically—no user-facing OAuth flow required.

To wrap it up:

• Stick with an API Key only if you just need to read data from a public sheet.
• For write access or private sheet access, go with OAuth 2.0 or a service account instead.

内容的提问来源于stack exchange，提问作者Ankush