Adding text to a PDF without Acrobat is entirely possible — the question is what kind of text you're adding. Filling in a form field, inserting a note, adding a label to a diagram, or correcting a specific word all work differently, and some methods are cleaner than others depending on the situation.
Browser-Based PDF Editor
For most text-adding tasks, a browser-based PDF Editor is the most practical free option. Open the tool in any browser, upload the PDF, select the text tool, click where you want to type, and add your content. The text appears as a new element positioned over the existing page — you can drag it to the exact location, adjust the font size, and change the color if needed.
This works well for adding information to specific spots: filling in a date field that was left blank, inserting a reference number, labeling a section of a diagram, or adding a short note in the margin. Font matching isn't perfect — if the original document used a custom typeface, your added text will probably be in a different font — but for most practical uses this doesn't matter much.
The key thing to understand is that the text you're adding sits on top of the page as a new layer. It doesn't modify the underlying content — it's an overlay. If you need to replace existing text rather than add new text, the approach is different: cover the old text with a white rectangle, then place a new text box on top with the corrected content. It's a workaround, but it's the standard approach when you don't have access to the source document.
Preview on Mac
Preview's Markup toolbar includes a text tool that works the same way. Open the PDF, click the pen-tip icon to reveal the markup tools, select the text box tool, click on the page where you want to add text, and type. You can resize the text box, move it around, and adjust font size using the formatting options that appear.
One thing Preview does well that browser tools sometimes miss: the ability to add text directly inside a form field on a fillable PDF. If the document has interactive form fields set up, Preview detects them and lets you click and type directly into them — the text appears in the correct field position without you having to manually position a floating text box. This is noticeably cleaner than the overlay approach for well-structured forms.
Adobe Reader (Free Version)
Adobe Reader — the free viewer, not the paid Acrobat Pro — includes a text commenting tool that lets you add text boxes anywhere on a PDF page. Go to Tools → Comment and look for the Text Box tool. The result is a properly saved annotation that any PDF viewer can display. For documents being shared with multiple reviewers, Reader annotations are more interoperable than text overlays created by some third-party tools.
Reader also handles fillable forms fully — if the PDF has form fields, they work exactly as intended. What the free version can't do is modify the underlying body text of the document or add form fields where none exist. That requires Acrobat Pro or a dedicated PDF editing tool.
LibreOffice Draw for Body Text Editing
If you need to actually edit existing body text in a PDF — not add a new element, but change what's already there — LibreOffice Draw is the only free desktop option that attempts this. Open the PDF in Draw and each text block becomes a separate editable object. Click on a text block to enter edit mode and change the content.
The honest caveat: LibreOffice Draw's PDF editing is imperfect. Fonts often substitute, text blocks don't reflow when you add more than a word or two, and complex layouts sometimes import incorrectly. It works well enough for simple documents where you need to change a specific word or number, but for anything involving significant text changes, converting to Word first and editing there is more reliable.
Which Method to Use
For filling in blanks, adding notes, or labeling things: browser tool or Preview. For form fields on a well-structured fillable PDF: Preview or Adobe Reader. For correcting existing text without going back to the source: the white-rectangle-plus-text-box workaround in any editor, or LibreOffice Draw for simple cases. For substantial text changes: convert to Word, edit, export back to PDF.