ChatGPT & API Magic – How to integrate external data into ChatGPT and save hours

What you learn

Custom GPTs can not only use their own knowledge, but also access external data sources live — via API actions. Mike shows how to build a GPT that reads tasks from Google Tasks, prioritises them and plans the day.

Key points

• Manually copying data from external tools into ChatGPT is unnecessary — API integration solves this

• You do not need to know how to programme: ChatGPT explains step by step and writes the technical schema itself

• API actions consist of two parts: authentication and schema (what is retrieved)

• Finished GPTs can be made available to the whole team

The Daily Tasks GPT in detail

System instructions:

• Read Google Tasks

• Assess urgency and importance (especially revenue relevance)

• Take deadlines into account

• Identify tasks that can be delegated

• Plan everything within 6 hours of work time

• End with a motivational boost

Example output:
"Finish Uni Bären — deadline today", "Campaign Review — Anna can help", "Adjust company addresses — by tomorrow, administrative"

Step by step

1. Create the GPT in the GPT Builder

2. Create a Google Cloud project

3. Set up an OAuth client (Client ID + Secret)

4. Let ChatGPT write the API schema automatically

5. Enter the schema and authentication in the action

6. Test: "What do I need to do today?" → GPT calls Google Tasks and delivers a prioritised list