PERRLA vs Paperpile: your sources, and the paper

It's the week your literature review is due. Your sources are saved, their PDFs are in your library, and each citation drops into your Google Doc in a couple of clicks. That part of Paperpile works well. Then you scroll back to the top. The title page, the heading levels, the margins, and the page numbers are still yours to set up, and nothing reads the finished paper against the APA format before you turn it in. That is where the difference between Paperpile and PERRLA starts.

What Paperpile does

Paperpile is a reference manager that runs in your browser. Its browser extension saves sources from Google Scholar, PubMed, arXiv, and publisher sites in one click and fetches the PDF when one is available. Your library lives in Paperpile's web app, sorted into folders and labels, with iOS and Android apps for reading on the go. Its plugins for Google Docs and Word insert in-text citations and footnotes as you write and build the bibliography in APA, MLA, Chicago, or any of more than 10,000 other styles. Several co-authors can cite in the same document.

There are two plans for individuals. Regular covers saving sources, storing and reading PDFs, and citing. Expert adds highlights and notes on PDFs, full-text search, shared folders, and syncing your files to Google Drive or OneDrive. Both are billed once a year.

What PERRLA does that Paperpile doesn't

Paperpile's plugins handle the citations and the bibliography. PERRLA handles the paper around them:

• Sets up the whole document in APA 7, MLA 9, or Turabian 9: title page, margins, spacing, page numbers, headings, and the references page or bibliography.
• Puts the citation where you are typing. Pick the source mid-sentence and the in-text citation lands in place.
• Builds the references page from what you cited, alphabetized, with hanging indents, and keeps it in sync when you add, move, or delete a citation.
• Reads the finished paper against the format when you click I'm Finished, and offers a one-click fix for most of what it finds.
• Shares one library across every place you write: PERRLA Online in your browser, the add-in for Word (desktop and web), and the add-on for Google Docs.

PERRLA's rule engine was written and tested by people against the APA, MLA, and Turabian manuals. It's deterministic: the same source gives the same reference every time.

Side by side

Saving sources from the browser

Paperpile's browser extension is one of the best things about it, and it's the first thing a Paperpile user asks about. PERRLA has one too. The PERRLA extension for Chrome and Edge puts an Add to PERRLA button on 85+ research databases, including Google Scholar, PubMed, JSTOR, ScienceDirect, and the CDC. One click looks the source up and fills in the reference in APA, MLA, or Turabian for you to check, then saves the article with it: the PDF when there is one, and a snapshot of the page when there isn't.

The snapshot is a readable copy of the page's text, attached to the reference, so the web page you cited in March still reads the same in May, even if the link breaks or your database access ends with the semester. Right-click any passage to save it to your Research Notes as a quote, with the source attached. If a source is already in your library, the button reads Open in PERRLA, so you don't add it twice. The extension is included in every PERRLA plan.

Paperpile's extension recognizes more sites and runs in more browsers. When a page has no PDF, Paperpile saves the reference with the page's title, URL, and access date.

More about the Chrome extension

Reading, notes, and Collections

Paperpile's PDF viewer is good, and on the Expert plan you can highlight passages and add notes. In PERRLA, every plan includes the Reference Annotator. Open a reference's PDF or snapshot inside PERRLA, highlight what matters, and pin a note to the exact passage with #tags. The note stays attached to its reference, and the page number travels into the citation when you use it. From Research Notes, insert a saved quote while you write and it lands at your cursor with its citation.

Collections hold the papers, references, and files for each project or chapter, nested however your work is built, and one source can sit in two Collections at once. You can start a new paper from a Collection with its references already loaded. The reader and Collections are in PERRLA Online; the library and citing work in Word and Google Docs too.

More about the research library

Where your PDFs live

Paperpile stores the files you add on its own servers, with no storage limit on any plan, and takes uploads up to 400 MB each. On the Expert plan it can also sync them to a Paperpile folder in your Google Drive or OneDrive. If a subscription ends, Paperpile keeps your account and data, and you can still sign in to export them. For a very large PDF library, Paperpile gives you more room for less money.

PERRLA keeps your files in your PERRLA account, attached to the references they belong to. Every plan includes 2 GB, which holds a few hundred article PDFs. PERRLA Pro raises that to 10 GB, and PERRLA Unlimited has no storage limit, with files up to 100 MB each. Papers never count toward storage, only the files attached to references and Collections. If a subscription ends, your files are kept for at least 90 days, and you can sign in to download your references as a .bib file, your papers, and all of your files, zipped.

Where Paperpile is the better tool

We won't pretend PERRLA is better at everything. Paperpile is the better pick when:

• You want the lowest price. With the academic discount, a year of Regular is $49.80.
• Your PDF library is very large. Storage is unlimited on every plan.
• You publish in a journal's style or write in LaTeX. Paperpile has more than 10,000 styles, BibTeX export, and, on Expert, Overleaf sync.
• You write with co-authors who all add citations to the same Google Doc or Word file.
• You read on a phone or tablet. Paperpile has iOS and Android apps.
• You want longer to decide. Its free trial runs 30 days.

If you're comfortable setting up your own papers and want an inexpensive library that cites quickly in Google Docs, Paperpile does that job well. PERRLA fits a student who writes APA, MLA, or Turabian papers and wants the whole paper formatted, from a weekly discussion post to a dissertation, with one library behind all of them.

Moving from Paperpile

Export your library from Paperpile as a BibTeX (.bib) file, then import it into PERRLA Online or the Word add-in, and your references come across. Paperpile's export leaves out the PDFs. Its help center says to download them as a ZIP file instead; attach the ones you're still using to their references in PERRLA. If you also keep a Zotero library, PERRLA connects to Zotero directly and brings across references, attached files, notes, PDF highlights, tags, and collections in one step.

A note on accuracy

Both tools fill in references from data on the web, and that data is sometimes thin: a missing issue number, an author's initials, a title in the wrong case. Paperpile formats with Citation Style Language styles, an open library of styles that volunteers maintain and many reference managers share. PERRLA looks sources up in the published record (the DOI registry, PubMed, and book databases like Open Library) and formats them with rules people wrote from the manuals, but no lookup is better than its source. Whichever tool you use, give each reference a glance before you submit.

A note on AI

Paperpile's Ask AI sends PDFs from your library to an AI assistant you already use, like ChatGPT, Claude, Gemini, Copilot, or NotebookLM, to summarize them or answer questions about them. If your syllabus limits AI tools, ask your instructor where that falls. PERRLA never writes or rewrites a word of your paper and never invents a source. In the software, AI is used in one narrow spot: when you upload a PDF of an article, AI reads its first pages to help fill in the reference, and the details are checked against published databases. Your paper is never sent to it.

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Questions about PERRLA and Paperpile