As suggested by @AndrewMBaines:
To cover embedding and using the API.
First off regarding the API see 
Using the REST API · metabase/metabase Wiki · GitHub
- Embedding in .Net with JWT : JWT embedding with .Net
- Java Embedding in a Java app - example - #3 by nplummer
- PHP/firebase: Embedd cards/dashboard in other applications - php examples with Firebase\JWT
Python (django), Ruby (rails), Node.js and PHP (laravel) examples are in:
Integrating using the REST API and C#: Using the REST API with .Net
If you want to start at a slightly higher level with interacting with the API than curl and 
Python is your thing and you just want to pip install metabase here’s a client lib:
Migrating Metabase Data using the API
Here’s link to the beginnings of a tool written to migrate questions and dashboards to multiple instances:
Some specific API call experiences
Does the parmeters go in as query string parameters or in the body. To URI encode — or not 
... that is always the question! If not the answer at least here are some of the experiences (including some answers):
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Finally - if you want/need to get rid of the Metabase logo (either to save precious screen space, want to "whitelabel" when you embed in your own product or service -- or simply because you would like to support their endeavor) the Metabase guys have this offering called Premium Embedding which they wrote about here:
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Wiki discussion:
To cover embedding and using the API. I think we should have a separate Wiki for working on the source code though.
@jornh: Got it! If it's sources for embedding I'm sure Pull Request's (PR's) to the GitHub - metabase/static-embedding-reference-apps: Reference applications for common web frameworks showing how to embed Metabase charts repo would be very well received by the Metabase core team
