This is the step where everything that worked in isolation suddenly does not. The backend is fine. The frontend is fine. They just refuse to talk. That is normal. Every founder who has shipped anything has stared at a CORS error or a wrong API URL for an hour and thought the project was broken. It was not. It was Tuesday.
Slow down. Debug one call at a time. Most integration bugs are typos.
When a button does not work, walk the request from start to end and ask one question at each hop:
Open the browser network tab. Read the actual request and response. Nine times in ten the answer is right there: a 401, a 404, a misspelled field name. Fix it. Move to the next call.
Ship to a real URL early. Vercel takes minutes. Local and live behave differently — environment variables, cookies, redirects all change. Catching a production-only bug on day one of integration is cheaper than catching it on launch day.
Bad: "the button does nothing." That is not a bug report, that is a feeling.
Good: "POST /entries returns 401 with cookie X but works with cookie Y." Now you can fix it.
Bad: chasing a bug for three hours by reading code.
Good: opening the network tab, seeing the response, fixing it in three minutes.
- Debugging by guessing. Read the actual request and response before you change a line.
- Skipping the live URL. Local-only testing hides half your real bugs.
- Stacking ten changes between tests. Change one thing, test, repeat.
Wire every button in your core flow to the endpoints you built in backend logic, ship to a live URL, and confirm the UI displays real data.
Every button in the core feature triggers the right request, the database reflects the change, and the UI renders the result on both your local environment and a live URL.
This is the step where everything that worked in isolation suddenly does not. The backend is fine. The frontend is fine. They just refuse to talk. That is normal. Every founder who has shipped anything has stared at a CORS error or a wrong API URL for an hour and thought the project was broken. It was not. It was Tuesday.
Slow down. Debug one call at a time. Most integration bugs are typos.
When a button does not work, walk the request from start to end and ask one question at each hop:
Open the browser network tab. Read the actual request and response. Nine times in ten the answer is right there: a 401, a 404, a misspelled field name. Fix it. Move to the next call.
Ship to a real URL early. Vercel takes minutes. Local and live behave differently — environment variables, cookies, redirects all change. Catching a production-only bug on day one of integration is cheaper than catching it on launch day.
Bad: "the button does nothing." That is not a bug report, that is a feeling.
Good: "POST /entries returns 401 with cookie X but works with cookie Y." Now you can fix it.
Bad: chasing a bug for three hours by reading code.
Good: opening the network tab, seeing the response, fixing it in three minutes.
- Debugging by guessing. Read the actual request and response before you change a line.
- Skipping the live URL. Local-only testing hides half your real bugs.
- Stacking ten changes between tests. Change one thing, test, repeat.
Wire every button in your core flow to the endpoints you built in backend logic, ship to a live URL, and confirm the UI displays real data.
Every button in the core feature triggers the right request, the database reflects the change, and the UI renders the result on both your local environment and a live URL.