Adobe Acrobat Pro costs $20/month and most people don't need it. For common PDF edits — adding text, filling forms, annotating, or signing — free tools handle the job.
For form filling and basic annotation, every major browser works. Open a PDF in Chrome, Edge, or Firefox and you can fill form fields, add text, highlight, and draw directly. Chrome even lets you add signatures. Save or print to PDF when done.
For adding text, images, or signatures to any PDF, fwip's sign tool works well. Drop your PDF, place text or a signature anywhere on the page, and download the result. Everything stays local in your browser.
For more substantial edits, LibreOffice Draw (free, cross-platform) can open and edit PDFs. It treats each page as a drawing, so you can move, delete, and modify text and images. The layout may shift slightly for complex documents, but for simple PDFs it works surprisingly well.
On Mac, Preview covers most annotation needs: highlighting, text notes, shapes, signatures, and form filling. It's built in and handles 90% of what people actually use Acrobat for.
For redaction — permanently removing sensitive content — you need a tool that actually removes the data, not just covers it with a black box. fwip's redact tool rasterises the page, which truly destroys the underlying text.