How should I correctly handle Spotify Web API 429 rate limits?

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Hi, I am a student building a small web project using the Spotify Web API. I am currently testing locally, and sometimes my app receives this error:

Spotify request failed (429)

I understand that 429 means the app is making too many requests too quickly. I want to handle this correctly and follow Spotify’s best practices.

My app needs to fetch playlist data, including large playlists with around 1,000–2,000 tracks. It may also need to perform playlist actions such as creating a playlist, adding tracks to a playlist, or removing selected tracks after user confirmation.

I am planning to improve my request handling by:

• Reading the Retry-After header when a 429 response happens
• Waiting before retrying
• Limiting concurrent Spotify API requests
• Caching playlist data
• Fetching playlist items page by page
• Adding tracks in batches instead of sending too many requests at once

I have a few questions:

1. When a 429 response happens, should I pause all Spotify API requests for that user until the Retry-After time passes?
2. What is the recommended way to fetch large playlists without hitting rate limits?
3. Should I add a small delay between paginated playlist requests?
4. For adding tracks to a playlist, is batching 100 track URIs per request the correct approach?
5. Is there a recommended concurrency limit for Spotify Web API requests in a web app?
6. Are there any best practices for caching playlist data to avoid repeated requests?

I want to make sure I handle rate limits properly and build the app in a safe and responsible way.

Thank you.