The Numbas Blog

We’ve had to take the server that powers the Numbas editor at numbas.mathcentre.ac.uk offline temporarily while we perform some maintenance.

We don’t currently have an idea of when we’ll be able to bring it back online; we’ll post updates here, on the numbas-users mailing list, and on the Numbas fediverse account.

• Update 2026-10-30: we’re still not back online. We might be back online next week, but no promises. Once we’ve got our servers back, we’re definitely going to have a look at how and where they’re run.

I’ve had to remove all of the XSLT code from Numbas, because browsers are dropping support for XSLT – see my previous post on how that could affect you.

This entailed a breaking change in the Numbas runtime, so I’ve increased the major version number to 11.

This post also lists other changes since the last development update, in June.

A while ago, Google announced that they would be removing XSLT support from Chrome, and other browser makers followed suit. That’s put us in a tight spot, because the Numbas default theme has always used XSLT to produce the displayed exam content.

On November 17th, 2026, the stable version of Chrome will disable XSLT, so any existing Numbas exam packages will stop working.

Update 2026-10-01: I’ve removed all of the XSLT code, so new Numbas exams will work without any problems on browsers without XSLT support. This is a big change for the compiler, so if you’ve written a custom theme, look at the notes for theme authors below.

Here’s how the removal of XSLT affects existing Numbas packages.

I’m pleased to announce the release of v10.0 of Numbas.

This release adds a new “notations” feature, making it easier to configure how mathematical expressions are interpreted and displayed. There are also several new options to make question parts more versatile, and some changes to avoid rounding errors in numbers.

I’ve put together a collection of question demonstrating the new features in this version. Read on for more detail about the changes in this release.

We’ve seen a few cases of genAI-generated .exam files on the Numbas editor. At present, generative AI tools do not have the innate ‘knowledge’ to make an exam file and will often lead to invalid or non-functional files.

If you are choosing to use generative AI to generate numbas exams, ensure that you provide links to the schema and documentation, and encourage the model to add appropriate descriptions to every variable and the question itself, including a note that it was generated by a genAI model.

Skill-enabled LLMs can use the json skill and the schema file to validate the schema, but can miss details on substituting in variables and marking algorithms, so you should always ensure to thoroughly test both correct and incorrect answers and look for edge cases, as well as ensuring question content itself makes sense.

We don’t plan to incorporate LLMs into Numbas.

It’s been quite a while since we last ran an online training session. We need to get back into it, so we’ve arranged one for Tuesday, 28th April 2026, 13:00 – 15:00 British Summer Time (UTC+1).

The training will take place on Microsoft Teams.

This will begin with an hour-long introduction for complete beginners, followed by an hour to look at advanced features and to answer your questions.

If you can’t attend this session, you might like to watch the recordings of the previous sessions.

To attend, please fill in the registration form.

This is an update gathering together changes made to the Numbas software in the last few months.

I’m pleased to announce the release of v9.0 of Numbas. This is a major release with an almost completely rewritten default theme, and some big structural changes inside.

We’re planning on releasing v9.0 of Numbas this Summer, hopefully on 19th August. This includes a completely rewritten user interface in the default theme, using newer browser features to improve accessibility and the user experience.

This means that some old browsers will not render Numbas exams correctly when using the new Standard theme.

The minimum supported browsers versions are as follows:

• Chrome version 112 (released 2023-04-04).
• Firefox version 117 (released 2023-08-29).
• Edge version 112 (released 2023-04-06).
• macOS Safari version 16.5 (released 2023-09-18, with MacOS Sonoma).
• iOS Safari (iPhone/iPad) version 16.5 (released 2023-09-18).
• Safe Exam Browser for Windows version 3.6 (released 2023-12-06).

We aim to ensure compatibility with at least 95% of browsers currently in use, as measured by MDN browser-compat-data. At time of writing, the features used by the new theme are supported by 95.82% of observed browsers.

We understand that it won’t always be possible to require students to use new browser versions straight away. For such situations, the old Standard theme will still be available within the Numbas editor, and existing custom themes will continue to use that as their base. The old theme does work with Numbas v9.0 but we won’t continue to update it and it doesn’t include any of the accessibility improvements.

Feedback on the new theme from our testers has been very positive, and we can’t wait to release it!

Here’s a round-up of development on the Numbas project over the last couple of months.

The most notable change is the addition of a “due date” field for resources in the Numbas LTI provider, so that late work policies can be accurately applied.