MarsEdit

 MarsEdit  is a Mac desktop app for blogging, supporting posting to several blog platforms including WordPress, Tumblr, and Micro.blog, maintained by Daniel Jalkut.

Daniel blogs about MarsEdit at: https://red-sweater.com/blog/

Features
MarsEdit can:
 * download posts,
 * create new posts,
 * edit and delete posts, and
 * upload files.

It works with most popular blogging services & software including Blogger, Movable Type, Tumblr, WordPress, and Micro.blog. It supports 3 very different APIs.

Standards support:
 * AtomPub standard (used for Google's Blogger)
 * MetaWeblog XML-RPC API (with flavors for the original Blogger API, Movable Type API, and the WordPress API)

Proprietary API support:
 * Tumblr API (custom JSON-based API)

MarsEdit will auto-discover the API type and endpoint using Really Simple Discovery (RSD): https://en.wikipedia.org/wiki/Really_Simple_Discovery

IndieWeb Support
MarsEdit does not currently support the Micropub API.

At IndieWebCamp Austin 2017, the MicroPub Life Cycle session discussed improvements to Micropub specifically with an app like MarsEdit in mind.
 * Micropub issues to resolve: ????

Origins
MarsEdit started as a blog posting feature in NetNewsWire by Brent Simmons. It was then expanded and moved into a standalone app. Daniel Jalkut of Red Sweater Software acquired the app in 2007 and he is still the current developer.