The history of Polar, the reading app that no longer exists

In November 2025, someone posted to r/Anki with a simple question: does Polar Bookshelf still exist?

They had discovered the app secondhand — told it could turn PDFs into Anki flashcards — and had gone looking for it. The Reddit thread they were reading linked to a betting site. A YouTube tutorial gave them enough context to type the right terms into Google; those led to the same betting site. They asked ChatGPT about Polar Bookshelf. ChatGPT gave them a friendly explanation, the app's old tagline, and the URL. The URL was the gambling site.

"Is this website still working???" they asked. "Does anyone know???"

Two days later, one reply: "Yeah it's gone. It was run by just one guy. He worked really hard at it but it never took off. I assume he cut his losses."

That is as close to an obituary as Polar has received.

Polar Bookshelf was, for a few years, one of the most-discussed reading tools on Hacker News. Its Show HN launch in October 2018 pulled 382 upvotes. At its peak the GitHub repo had around 4,500 stars. The developer claimed about 5,000 monthly active users. The app appeared in PKM-focused roundups and "second brain" tool lists throughout 2019 and 2020.

Today, the domain it lived at — getpolarized.io — has been taken over by squatters who cycle users through gambling-affiliate traffic. The main GitHub repository has been deleted. The founder has never publicly explained the shutdown. And people like the Anki poster above keep discovering Polar through old tutorials and AI chatbots, keep clicking the old URL, and keep landing somewhere they did not intend.

This is a short history of how that happened.

2018: local-first, open source, and a lot of hype

Polar launched in October 2018 as a local-first reading and annotation tool for PDFs, EPUBs, and captured web pages. It was built by Kevin Burton, a solo developer. The stack was Electron and TypeScript on top of Firebase auth; files were stored locally by default; the code was Apache-2.0 licensed on GitHub under burtonator/polar-bookshelf.

The pitch worked. The Show HN post drew hundreds of upvotes and a long comment thread. Early adopters liked the local-first story — PDFs stayed on your disk, highlights stayed yours, sync was optional. The personal-knowledge-management and incremental-reading communities, especially, latched on to Polar as the thing their workflow had been missing: an Anki-compatible spaced-repetition layer on top of PDFs they already read. The subreddit r/PolarBookshelf appeared. The project gained stars. For a few months after launch it looked like the right project at the right time.

It also looked, from the founder's own posts, like a project he was already struggling to fund.

2019: the frustration arc

Three months after launch, in January 2019, the founder posted on Hacker News: "I've literally LOST money open sourcing this... I'm -$1250 or so at this point."

In March, he asked for donations: "If you like Polar please consider donating... we've received essentially zero Open Source contributions from the community and very little funding."

In April, he put it more bluntly: "we've only raised about $500... I've probably made about $0.15 per hour... Consumers hate paying for software."

The same month, he launched a crowdfunding plea titled "Help me reboot the Internet", which earned 428 upvotes on Hacker News but did not materially change the economics. He framed users who had said they would donate around $27 on average as the community "failing to follow through."

There is nothing unusual about a solo developer running out of money. The noticeable thing, reading those posts now, is what the developer pointed at.

The Hacker News upvotes, the GitHub stars, the r/PolarBookshelf subreddit — the hype that had put Polar in front of developers in the first place — were reframed as a community that owed him. Users were "Consumers" who "hate paying for software." Stars and forks were "essentially zero Open Source contributions." A project that had leveraged open-source visibility to gain traction was publicly blaming open-source users for not also funding it.

This is a pattern worth watching in any early-stage tool. A developer whose public voice frames users as counterparties who owe them, rather than as customers to earn, is making a prediction. The tool will be worth what users are willing to donate to it — which, the developer will remind them, is never enough. When the funding gap can no longer be papered over with Stripe buttons and blog posts, something has to give. It rarely gives in the users' favor.

By October 2019, the founder described Polar as having about 5,000 monthly active users in a post looking for a co-founder.

A year later, Polar pivoted.

October 2020: the cloud-only pivot

On October 27, 2020, Show HN: Polar 2.0 appeared on the front page.

The new version was a different product. Local-first was gone. Polar 2.0 was cloud-only,...