Add real, properly typeset mathematical equations directly onto any PDF — in your browser, in under a minute. No LaTeX installation, no compilation step, no upload.
Open AnnotariumMost PDF annotators only let you add plain-text comments. That's fine for "good work" or "expand on this", but it falls apart the moment you need to write mathematics. Typing integral from 0 to 1 of x squared dx is awkward; what you actually want is
$\int_0^1 x^2 \, dx$
rendered properly on the page. Annotarium does this directly — without installing TeX Live, without uploading the PDF anywhere, and without compiling.
Go to app.annotarium.org and open your PDF: drag and drop it onto the workspace, or click Open PDF. The PDF is loaded into your browser and stays on your device — nothing is uploaded.
Press T or click the LaTeX tool in the toolbar. Click anywhere on the page where you want an equation. A small editor opens at that position.
Type LaTeX in the editor. Common patterns:
$x^2 + y^2 = r^2$ — inline equation$$\frac{d}{dx}\sin(x) = \cos(x)$$ — display equation$\int_0^\infty e^{-x^2}\,dx = \frac{\sqrt{\pi}}{2}$ — integral with limits$\begin{pmatrix} a & b \\ c & d \end{pmatrix}$ — matrixPress Enter (or click outside) to render. The equation appears on the page as a properly typeset annotation.
Drag the equation to position it. Use the corner handles to resize. Use the rotation handle if you need to fit a margin annotation. The equation stays vector-quality at any size.
When you're done, use File → Save. Annotarium bakes the equations into the PDF as part of the page, so the exported file opens correctly in any reader (Preview, Acrobat, Chrome's built-in viewer) without needing Annotarium installed.
T for LaTeX tool, V for cursor.$...$ for inline; $$...$$ for display (centered, larger).Yes. Annotarium uses KaTeX to render the equation and embeds it as part of the PDF page on export, so the equations remain crisp at any zoom level and open correctly in any PDF reader.
Annotarium supports the standard mathematical commands available in KaTeX, which covers the majority of common notation including amsmath-style fractions, integrals, matrices, and aligned equations. See the KaTeX support reference for the full list.
Press T to switch to the LaTeX tool. Press V to return to the cursor.
No. KaTeX renders equations synchronously, so the equation appears as soon as you finish typing — there is no compile step.