Placemark, a startup, is shutting down due to inability to achieve sustainability. The founder, Tom MacWright, will release the full source code of the site later in January, after turning off signups and allowing existing customers to use it for free until January 19, 2024. The founder reflects on the experience of building Placemark, noting it was fun but failing to find success was hard. The code will be open-sourced, potentially allowing it to live on as a community-maintained project.