Easy to start, easy to expand, easy to understand – for you and for your team. I’ve linked to some knowledge management tools before I believe and while they aren’t specific to software development, I think developers can really benefit. I’ve used Zenkit before as a Trello alternative, but this Hypernotes product looks like it takes things to the next level. You can get 2 notebooks of 10,000 notes each to use for free, which for many may be all you need. There are team and collaborative features as well, making this less of a personal knowledge management tool, but one that might be able to fill the role of wiki and/or knowledge base for a team or organization.