Automate Todoist Task Prioritization Using n8n and OpenAI

1. Opening Problem Statement

Meet Sarah, a freelance project manager juggling multiple projects and dozens of daily tasks in Todoist. Sarah spends over an hour each day manually prioritizing her inbox tasks to ensure urgent work is handled first. Despite her efforts, some tasks slip through the cracks due to inconsistent categorization and priority assignment, leading to missed deadlines and stress.

Sarah’s pain is all too common: manually sorting and prioritizing tasks can drain valuable time, create errors, and reduce productivity. What if her Todoist priorities could update themselves intelligently, freeing up her time and mental space?

2. What This Automation Does

This n8n workflow uniquely combines Todoist and OpenAI to automate task categorization and priority updates. When triggered on a schedule, it:

• Fetches all tasks from Sarah’s Todoist inbox project.
• Filters out subtasks to focus only on top-level tasks.
• Uses the OpenAI GPT-4o-mini model to categorize each task into predefined projects (like “apartment,” “health,” or “german”), or marks it “other” if no match.
• Checks the categorization; if valid, updates the task’s priority in Todoist accordingly.
• Retries API calls if they fail, ensuring reliable automation.

By automating this intelligent prioritization process, Sarah saves over an hour daily and guarantees consistent task handling based on meaningful categories.

3. Prerequisites ⚙️

• Todoist account with API access (todoist API credentials to connect via n8n)
• OpenAI account with API key for GPT model use
• n8n account to create and run workflows (self-hosting optional — see Hostinger self-host guide)

4. Step-by-Step Guide

Step 1: Set up the Scheduled Trigger

In n8n, click “+” to add a node. Select Schedule Trigger. Set it to run at your preferred interval (e.g., every hour). This node fires the workflow regularly to scan your Todoist inbox.

Expected: The workflow initiates on schedule, no manual input needed.

Common mistake: Forgetting to set the trigger interval, causing the workflow not to run.

Step 2: Define Your Projects and Priorities

Add a Set node named “Your Projects.” Enter your project names as keys with associated priority values as numbers. For example:

{
  apartment: 1,
  health: 2,
  german: 3
}

This creates a simple object that maps your task categories to Todoist priority values.

Expected: Projects object available for reference downstream.

Common mistake: Typos in project names that cause failed lookup.

Step 3: Retrieve Inbox Tasks from Todoist

Add a Todoist node, set to “Get All” tasks from your inbox project by its specific project ID (replace with your actual Inbox project ID). Enable “Return All” to fetch every task.

Expected: Array of Todoist inbox tasks available in the workflow.

Common mistake: Setting the wrong project ID or forgetting to return all tasks.

Step 4: Filter Out Subtasks

Add a Filter node named “If task is not a subtask.” Configure it to check if the task has an empty parent_id, meaning it’s a top-level task.

Expected: Only main tasks progress for categorization.

Common mistake: Misconfiguring condition, allowing subtasks to pass through.

Step 5: Use OpenAI to Categorize Tasks

Add the OpenAI (LangChain) node. Use the GPT-4o-mini model. For the prompt, include your projects and the task content, asking to categorize the task or return “other” if no match. Example system message:

=Categorize the user's todo item to a project. Return the project name or just "other" if it does not belong to a project.

Projects:
{{ $('Your Projects').first().json.projects.keys().join('n') }}

Todo item:
{{ $('Get inbox tasks').item.json.content }}

Expected: Response with project name or “other.”

Common mistake: Prompt formatting errors reducing AI accuracy.

Step 6: Validate AI Categorization

Add another Filter node “If other or ai hallucinates.” Configure it to check if the AI response is part of your project keys. Tasks marked “other” or invalid do not proceed.

Expected: Only valid project names trigger priority update.

Common mistake: Not properly handling “other” causing errors in update.

Step 7: Update Task Priority in Todoist

Add a Todoist node: Update Operation. Set Task ID from the original task’s ID. For priority, select the corresponding value from your projects mapping based on AI categorization.

Expected: Task priority updated automatically.

Common mistake: Mapping errors causing wrong priorities.

Step 8: Add Sticky Notes for Setup Guidance (Optional)

For easier onboarding, add multiple Sticky Note nodes to display setup instructions such as adding credentials or project mappings.

Expected: Clear setup guidance within the workflow editor.

5. Customizations ✏️

• Add More Projects: In the “Your Projects” Set node, add more key-value pairs to expand your task categories and assign priorities accordingly.
• Change AI Model: Swap the LangChain OpenAI node model ID to a different GPT variant for varied precision or cost savings.
• Include Subtasks: Modify the filter to allow subtasks to be processed if that fits your workflow better.
• Adjust Trigger Frequency: Change the schedule trigger interval to run more or less often based on your task inflow.
• Enhance AI Prompt: Customize the prompt in the LangChain node to fine-tune categorization criteria for your specific task types.

6. Troubleshooting 🔧

Problem: “Todoist API rate limit exceeded or task not updating.”
Cause: Too many update attempts or invalid task ID.
Solution: Check credentials, verify task IDs, and ensure retries are configured in the Todoist node settings.

Problem: “AI response is empty or inaccurate categorization.”
Cause: Incorrect prompt format or model issues.
Solution: Review and refine your prompt phrasing in the LangChain OpenAI node.

7. Pre-Production Checklist ✅

• Verify your Todoist credentials and project IDs are correct.
• Test the scheduled trigger by running the workflow manually.
• Confirm tasks fetched from Todoist match expected inbox tasks.
• Check the AI categorization returns valid project names or “other.”
• Ensure the Todoist update node correctly changes task priority.

8. Deployment Guide

Activate your workflow by switching it ON in n8n after completing setup. Monitor execution logs to ensure tasks categorize and update properly. Adjust the schedule as needed. If running many tasks, consider API usage limits.

9. FAQs

Q: Can I use other AI models with this workflow?
A: Yes, you can swap the GPT-4o-mini model for others supported by the LangChain OpenAI node.

Q: Does this workflow consume many OpenAI tokens?
A: Token usage depends on task content size and frequency; use shorter tasks or reduced schedule to lower cost.

Q: Is my Todoist data safe?
A: Yes, your credentials are stored securely in n8n, and API calls are encrypted.

10. Conclusion

By following this guide, you’ve automated your Todoist inbox task prioritization with intelligent AI-driven categorization. This saves hours daily by eliminating manual sorting and ensures your focus stays on what matters. Consider next automations like integrating deadline reminders, syncing with your calendar, or automating task comments for updates.

Enjoy your new productive workflow and the peace of mind it brings!