This website allows you to convert LaTeX math into MathML (or, more specifically, MathML Core), which is then rendered by your browser. For example, try this input:
\int \mathcal{D}\!x =
\lim_{N \to \infty}
\left( \frac{m}{2\pi i \hbar \Delta t} \right)^\frac{N}{2}
\int\!\cdots\!\int \prod_{i=1}^{N-1} dx_iRecent versions of all the major browsers support MathML Core, so you should be able to see the rendered math.
The conversion runs entirely in your browser, using WebAssembly and a tiny bit of JavaScript. Your LaTeX math is never sent to a server. The compiled WebAssembly is under 100kB; less than many images on the web. Additionally, this webpage needs a patched version of the Latin Modern Math font, to render primes correctly on Chromium-based browsers. The font file for that is 375kB.
Not all features of LaTeX math are supported. Some of them simply because they haven’t been implemented yet; others because they are very difficult to translate into MathML.
If you need multiline equations, you can use the
environments \begin{aligned},
\begin{align}, or \begin{align*}.
For example:
\begin{aligned}
x &= 1 \\
y + z &= 2
\end{aligned}