How to Update Your n8n Workflow for Gamma API v1.0

Critical Update: Gamma API v0.2 Sunset

If you're using Gamma's API with n8n to automatically generate presentations, you need to update your workflows before January 31, 2026. Gamma is deprecating their v0.2 API endpoints, and any workflows still using the old version will stop working after this date.

The good news? The migration is straightforward and takes just a few minutes. This guide walks you through exactly what needs to change.

What's Changing in Gamma API v1.0

The most significant change in the v1.0 API is how themes are specified. Instead of using human-readable theme names, the new API requires theme IDs.

Old way (v0.2):

"themeName": "Oasis"

New way (v1.0):

"themeId": "theme_abc123xyz"

This change improves API stability and allows for more precise theme selection, but it does require a one-time update to your workflows.

Step-by-Step Migration for n8n Users

Step 1: Open Your n8n Workflow

Navigate to your n8n instance and open the workflow that uses the Gamma API. Look for the HTTP Request node that makes the API call to Gamma.

Step 2: Update the API URL

In your HTTP Request node, change the URL from:

https://public-api.gamma.app/v0.2/generations

To:

https://public-api.gamma.app/v1.0/generations

Step 3: Get Your Theme ID from Gamma

This is the crucial step. Here's how to find your theme ID:

Log into your Gamma account at gamma.app
Click the palette icon in the navigation bar to open the Design Library
Find the theme you want to use for your presentations
Click the three dots (⋯) next to the theme name
Select "Copy theme ID for API" from the menu

Your theme ID will be copied to your clipboard. It will look something like: theme_12345abcde

Step 4: Update Your JSON Payload

In your n8n HTTP Request node, find the JSON body section. Replace the themeName parameter with themeId:

Before:

{
  "inputText": "Your presentation topic",
  "format": "presentation",
  "themeName": "Oasis",
  "numCards": 10
}

After:

{
  "inputText": "Your presentation topic",
  "format": "presentation",
  "themeId": "theme_12345abcde",
  "numCards": 10
}

Step 5: Save and Test

Save your updated workflow. If you're using n8n v2.0+, publish the new version. If you're on v1.x, activate the workflow.

Run a test execution to verify everything works correctly with the new API version.

Alternative: Use Gamma's Default Theme

If you don't need a specific custom theme, you can simplify your migration by removing the theme parameter entirely. The v1.0 API will use Gamma's standard default theme automatically:

{
  "inputText": "Your presentation topic",
  "format": "presentation",
  "numCards": 10
}

What If I Have Multiple Workflows?

If you have several n8n workflows using the Gamma API, you'll need to update each one individually. However, the process is identical for each workflow:

Update the API URL to v1.0
Replace themeName with themeId
Use the same theme ID across all workflows (or get different theme IDs if you want different themes)

Consider documenting your theme IDs in a central location so you can easily reference them when creating new workflows.

Additional Resources

Need Help?

If you run into issues during the migration, double-check that:

Your API key hasn't changed (it should remain the same)
You've copied the complete theme ID from Gamma
You're using the correct v1.0 endpoint URL
Your JSON syntax is valid (watch for missing commas or quotes)

The January 31, 2026 deadline is approaching quickly, so make sure to update your workflows soon. The migration is straightforward, and once complete, your automated presentation generation will continue working seamlessly with the improved v1.0 API.