The mempool.observer website displays visualizations about my Bitcoin mempool. For example, a visualization of my current mempool and the historical mempool of my node is shown. The idea is to provide information about the current mempool state to a Bitcoin user with a seemingly stuck and longtime-unconfirmed transaction. Additionally, the site can be used for double-checking feerate estimates before sending a transaction.
I started working on the 2019 version in April 2019. The 2019 version is a full rewrite of mempool.observer - only the idea and license remained. The goal is to offer way more than the 2017 version did, but built on a foundation with performance and maintainability in mind as this was a problem in the 2017 version. Timothy Lim @timothyylim helped out by contributing to the frontend.