Thirteen years ago, on a quiet Saturday night, I sat down and began developing MathB.in. After coding all through the night, as the sun rose on Sunday, 25 March 2012, the website was ready. I registered a new domain name and shared it with a few friends who loved mathematics. Back then, we spent hours discussing fascinating mathematics problems and this website became a simple way for us to share snippets with each other. Word spread quickly. My friends shared it with their friends, who passed it along to others. The community grew organically. Then, one day, I announced the project on the MathJax mailing list and its reach expanded even further. Within a year, this mathematics pastebin service had users from around the world. Watching the usage of this little project grow was an incredibly rewarding experience.

A screenshot of MathB.in, a mathematics pastebin service

The world has changed a lot since I first published MathB.in. The internet has evolved and so have I. Maintaining a mathematics pastebin service like this single-handedly has become increasingly difficult over the years. Over the past 13 years, I have received notices from regulatory authorities whenever someone submitted content that triggered compliance concerns. Each time, my server would be taken offline and I would be given a 7-day deadline to boot it into rescue mode, remove the offending content and restore service. Missing the deadline would put my server hosting account at risk of cancellation.

To prevent these disruptions, I began reviewing and filtering incoming content as much as possible every few days. The appreciation and positive feedback from happy users kept me going. However, at this stage of my life, I can no longer afford to spend time moderating user content. On top of that, the growing complexity of data protection and digital safety regulations places a significant burden on me as the maintainer of this service. Complying with these regulations requires considerable legal expertise that I cannot afford.

Some might suggest that I could improve the spam-detection capabilities of this service and indeed, I have done so over the years. However, all anti-spam measures are inherently probabilistic. No matter how much automation is in place, a manual review of every post is still necessary to guarantee that all content is legitimate. It only takes one dodgy submission to trigger compliance alerts. While I respect the need for these regulations, I do not want to spend my weekends worrying about what users from around the world might be posting on this little pastebin service. Nor do I want to be in a constant state of vigilance just to keep my server running. It takes up more time than I can spare.

Some have suggested forming a team of volunteers to review submissions, but that does not solve the core issue: since the server hosting account is in my name, I would still be responsible for remediating any compliance issues or risk having my account cancelled. Another alternative is to move the service under a non-profit organisation, but with increased responsibilities in other areas of my life, handling the operational demands of such an endeavour is far beyond what I can commit to. After all, this was meant to be a fun project built for me and my friends, not something that requires me to deal with regulatory issues.

Another alternative would be to encode the content of a MathB.in post and embed it into the URL, which could then be distributed with others. Upon visiting the URL, the application would read the encoded content from the URL, decode it and render it. While this eliminates the need to store user content on my server, it introduces a new concern: the risk of someone sharing URLs with malicious content embedded in them. I am not comfortable with such content being rendered on a page served from a domain that I am the registrant of. The regulatory implications of rendering such content are also unclear. I could still be held accountable for content rendered on the website, regardless of whether it's stored on the server. This problem could be mitigated to some extent by refusing to render content containing known malicious patterns but no such solution can be foolproof.

As a result, after much thought, I have regrettably made the decision to shut down MathB.in on Sunday, 16 March 2025. The website will go offline on that day. If you have any important posts that you would like to keep, now is the time to copy and save them for yourself.

To all of you who have used this project, I want to express my sincere gratitude. Running a project that could serve you in a meaningful way has given me a strong sense of accomplishment and pride. To those who are disappointed by this service's closure, I am sorry. I wish I could continue to dedicate the time and effort needed to maintain and develop it, but I must acknowledge my limitations and step away from a project that has become an artefact of my past, not my present.

The source code for this website is available at github.com/susam/mathb under the MIT licence. Feel free to use the code and set up your own instance if you'd like! Alternatively, consider hosting your mathematical snippets and notes on your own web space using a kit like MathCask available at github.com/susam/mathcask.

Finally, I hope you'll hold no hard feelings. If you have enjoyed using MathB.in, I would love to stay connected on the Fediverse. My Mastodon handle is @susam@mastodon.social. See you there!