KnifeLemon/Filee · KnifeLemon

A donut got 22k stars: How Filee made the old "file converter" hot

What it is: A free, open-source Windows file converter. Drag a file and a ring-shaped format menu pops up next to the cursor. Drop onto a format and it converts. Offline, no Office install needed, supports 260 formats including Korea's HWP.

Why it took off: A single animated GIF of the "cursor donut" explains it, which makes it very shareable. Add offline and no uploads, broad format coverage, and HWP as a must-have in Korea, and it spread for free through Reddit, Chinese and Korean software sites, GitHub Trending, and AI content farms.

BHow you could follow it Don't build another converter donut. Copy the approach instead: take an old tool like compression, renaming, or background removal, and give it a new interaction that explains itself in one shot. Ship a multilingual README, have the author post on Reddit personally, and release often. Or build the native macOS version it didn't do well.

Grade B: the approach is clear and copyable, and it can earn stars. But Filee itself has been widely covered, and OrbitDrop, which copied it directly, has only 63 stars. Followers have to find a new category and an equally shareable interaction, and that is a bet. Already public / widely discussed

Data (updated daily) · Repo created 2026-09-29 · 23,602 stars · 7 days +4,350: GitHub · stars
Data 2026-10-09 → 2026-11-08 (31 days, 30 observations). Points before 10-28 come from deeply / archive backfill, not every day has one

In late September, Korean developer Kim Myung-gu (KnifeLemon) created a repo for something many people have built: a free, offline desktop file converter. 38 days later it had 22.9k stars and 720k installer downloads. The features aren't new. The new part is one gesture: hold Ctrl, drag a file, and a ring of formats appears at the cursor. Let go and it converts. This piece covers how it took off, and what you can borrow and what you can't if you want a project that earns stars the same way.

"gif to png" "hwp to pdf"

On Oct 6, Kim (GitHub name KnifeLemon) published an introduction on Disquiet, a Korean product community. It opens like this: when you want to change a file's format, you type gif to png or hwp to pdf into the search box, and it happens more often than you'd think. Converting a few images with an online tool is fine, but uploading documents and work files always feels uneasy. Installing software means opening a program, finding the file, and picking a format every single time.

So he thought: could you convert right there in Explorer, where the file already is? He said the thing he cared about most in building Filee was less the conversion itself and more reducing the steps it takes to convert.

Here's what he built: hold Ctrl and drag a file, and a small ring menu appears around the cursor listing only the formats that file can convert to. Drag a HEIC and you get JPG, PNG, WEBP. Drag a PDF and you get DOCX, HWPX, and images. Drop onto a format and the result is saved next to the original. No window, no uploads, no usage data collected. No Office install and no Hancom (the HWP software used by Korean governments and schools) needed, and you can still convert HWP to PDF or Word.

How fast it grew

The repo was created in Sep 29. An Oct 12 article headline read "403 stars". 10-16 816,10-20 5,997,10-28 15,314,11-06 22,545 (GitHub, daily star counts). The GitHub API reads 11-06 22,932 stars and 1,369 forks.

The two biggest days: 10-19 to 10-20 added +2,280 in a single day, and 10-27 to 10-28 added +2,445 in a day. That day it shipped v2.2.0, a Chinese product-manager blog published a long post about it, and HelloGitHub featured it.

It's cooling now: the last 7 days +5,200, and the 7 days before that were +8,421, but it still adds 600–700 a day.

Beyond stars, people are installing it. Across 30 versions, installer downloads total 724k (GitHub API, 11-06): v1.12.0 (10-19) 112k downloads, v2.2.0 (10-28) 206k. The app prompts for updates, so some of these are existing users upgrading, and the numbers only show scale. Microsoft Store and winget install counts aren't public and are not included.

From 9-29 to 11-03 it shipped 30 versions, nearly one a day. The PRs carry Co-Authored-By trailers, and he also posted the project to r/OnlyAICoding under the tag "Something I Made With AI". One person, AI-assisted, shipping a release every day.

Where the users come from

No money was spent. It was a relay.

Reddit, posted by the author himself. 10-02 posted on r/software, 79 upvotes and 64 comments; the same day he also posted to r/windowsapps and r/OnlyAICoding. Later, Reddit users came back with the files that broke and reported bugs, and some of those requests turned straight into PRs.
Korean circles. 10-06 posted on Disquiet, then people recommended it on their own on Naver blogs and Threads. The pitch was one line: you can convert HWP to PDF without Hancom.
Chinese software sites, first to arrive and biggest in volume. 10-11 Keji Shi, 10-12 puresys released a portable version, 10-15 Xiao Yi, 10-16 Tencent Cloud Developer Community, 10-18 two posts on GitCode, 10-28 Everyone is a Product Manager (headline "gained nearly 14k stars"), plus Zhihu, Bilibili, and HelloGitHub. The README is in 17 languages, with both Simplified and Traditional Chinese, so reposters can use it as-is.
GitHub Trending. The README displays a Trendshift badge reading "C# daily / weekly #1", and a Korean YouTube video title reads "GitHub weekly #9". From 10-19 to 10-21 it gained 1,700–2,300 stars a day, which looks a lot like a spot on the site-wide Trending page (inferred; I did not confirm which day it landed).
AI content farms and short video. Once it charted, a batch of blogs claiming to be "written by AI from the source code", one-minute project Shorts in Japanese, Korean and English, Instagram Reels, and automated GitHub recommendation groups on Facebook followed. From 10-24 to 10-30 they formed a second wave. TikTok was small, with the top video at 46k views.
Media came last. German Netzwelt 10-27, MakeUseOf 11-03, both after the peak had passed.

What didn't work: launched on Product Hunt with 10-10 upvotes, 1 votes; no Hacker News posts about it at all.

Why this one

Plenty of similar projects: Tichau/FileConverter has existed for 2015 years with 15.6k stars, also convert-on-right-click; VERT converts locally in the browser, 16.2k stars; ConvertX is self-hosted, 19.5k stars. Filee overlaps heavily with them in features.

People share it almost entirely because of that donut. "Hold Ctrl and drag → a ring pops up at the cursor → release and it converts." A 27-second GIF explains it all, which makes it a natural fit for READMEs and short videos, and nearly every article headline is about it.

The remaining reasons are why people feel safe installing it and keep it:

Fear of uploading. Netzwelt's headline was "Still uploading contract PDFs to sketchy online converters?" Offline, open source, and zero telemetry address exactly that anxiety.
Enough formats. It grew from 180 formats to 263. MakeUseOf's headline said it "makes it harder for a dozen small apps to justify existing."
A local must-have. HWP is a real pain point in Korea, so there was a group of genuine users from the cold start.
Fixed fast. Releases ship daily, and feedback from Reddit and issues gets fixed the same day, so word of mouth kept rolling.

Others are already following

OrbitDrop (10-18 created the repo): on Windows, hold Shift to bring up a radial wheel. It posted on r/foss saying "I built a free app that converts files without opening anything." 11-06 has only 63 stars.
Tangerine (r/macapps, about 10-27): a paid Mac app with drag + Shift to convert. In the comments someone posted a Filee link directly, and others said it was too expensive.
A web-based "drag-and-drop format wheel" converter has also appeared on GitHub.

OrbitDrop shows one thing: redoing the same interaction in the same category doesn't earn stars. People already know Filee, and a second donut isn't news.

If it were you

One judgment call: don't copy Filee itself, but its playbook is worth copying. The opportunity is in "building a new interaction for another familiar tool that can be explained in one GIF," not in file conversion.

Who it suits: developers who can build desktop or system-level small tools, are willing to ship daily, and will reply to people on Reddit themselves. Having a local need in a small language or a specific country (like HWP) is even better.

Who it doesn't suit: anyone who wants to make money from it (Filee states it has no ads and no paid tier, and copycats won't earn from it either); people who can only build web apps and can't deliver a "lives on the cursor" system-level experience; people without the energy for high-frequency iteration in the first month.

How to do it:

Switch categories: compression, batch renaming, background removal, OCR, screenshot-to-text, color picking... Pick an action everyone does daily but currently requires opening a program or webpage each time, and move the entry point to drag-and-drop, the cursor, or a hotkey. Work out the GIF first. If the GIF can't explain it, don't build it.
Switch platforms: Filee's macOS version is still a preview. A native, free, open-source Mac app with the same kind of experience is the gap it hasn't filled. But be ready for a head-to-head fight with Tangerine and Filee's own Mac version.
Add a local hook: find a format or workflow that big tools ignore and that people in a particular country run into every day, so the cold start has a group of people who really need it.

How to acquire users: follow its sequence. On day one, the author posts on boards like r/software and replies to every comment. At the same time, make the README in 5+ languages (at least Chinese, Japanese, Korean, and English). Chinese software sites and HelloGitHub will find you on their own, but you can also submit proactively. Once you hit Trendshift and GitHub Trending, AI blogs and Shorts will amplify it for free. Product Hunt is basically useless for this kind of thing.

When to move before it's too late: the novelty of "converting right at the cursor" probably has one or two months left. Switching categories has no obvious deadline, but the more people copy this playbook, the less "another donut" looks like news.

Signs you've misread it: a week after posting, the Reddit thread hasn't reached a few dozen upvotes and stars stall at a few hundred; or the comments mostly say "Filee already does this." That means your interaction isn't new enough. Change categories rather than pushing harder.

GitHub repo ↗

Research notes: competitor table, acquisition evidence, full research report

Competitors

Name	Where	Launched	Scale	How it differs from this one
Tichau/FileConverter	Open source	2015	15.6k star	Only a Explorer right-click menu, few formats, no HWP/Office conversion, no cursor radial menu
VERT	Open source	2024-11	16.2k star	WASM local conversion in the web page; you have to open the site first
ConvertX	Open source	2024-04	19.5k star	Self-hosted server, aimed at technical users
Transmute	Open source	2026-02	1.5k star	Self-hosted
CloudConvert / Convertio / FreeConvert / Smallpdf	Web	Early on	Large (unverified)	Requires uploading files; size limits and a paywall
Format Factory / HandBrake / Permute	Other	Early on	Big	Open a window and pick a format; most handle only audio and video
PowerToys, macOS Quick Actions	Big-company features	Early on	Built into the system	Converts only a few image formats
이음오피스 / Hancom Viewer / ONLYOFFICE	Other	Early on	Korean local	Can open HWP, but can't convert with a single drag

Where users come from

Verified Reddit (author posted personally): 10-02 on r/software, 79 upvotes / 64 comments; same day posted to r/windowsapps and r/OnlyAICoding; the author said on Disquiet that Reddit users were reporting issues
Verified Korean communities (Disquiet, Naver blog, Threads): 10-06 the author posted on Disquiet; datanexus 10-12, giting 10-19; the selling point was converting HWP without Hancom
Verified Chinese software sites and tech communities: Keji Shi 10-11, puresys 10-12, Xiao Yi / Diao Software 10-15, Tencent Cloud 10-16, Jianke.com 10-17, Everyone is a Product Manager 10-28, HelloGitHub, Zhihu, Bilibili
Inferred GitHub Trending / Trendshift: README shows a Trendshift C# daily / weekly #1 badge; a Korean YouTube title says GitHub weekly #9; from 10-19 to 10-21 it gained +1.7k to 2.3k per day
Verified AI content farms / YouTube Shorts / Instagram Reels / Facebook groups: Reveneau self-described as AI-written; airanks, frontiernow, devpik, admin365 and others publish in batches; multilingual Shorts; Facebook githunt
Verified X main accounts: @Gorden_Sun 11-01 posted Chinese tweets
Verified Media: Netzwelt 10-27, MakeUseOf 11-03 (both after the peak)
Verified TikTok: @cubesites 46k views, @jifryissadeen 14k views, small volume
Verified Product Hunt: 10-10 launch, 1 votes, no effect (our producthunt database)

Why Filee (KnifeLemon/Filee) took off

Research date 2026-11-06. Data comes from the GitHub API, our github and producthunt databases, and web search via Jina / Exa / Brave. All sources are listed at the end.

One line

Filee is a free, open-source (MIT) desktop file converter built by Korean indie developer Myeonggu Kim (GitHub handle KnifeLemon). It's written in C# and Avalonia, mainly for Windows, with a Linux version and a macOS preview. You hold Ctrl and drag a file, a circular format "donut" menu pops up at the cursor, and you drop the file onto the format you want and it converts, with the output saved next to the original. Everything runs offline, with no need for Office or Korea's Hancom Office (Hancom is used to open Korean HWP documents). Why it took off: the "file converter" need is widespread and old, but using existing ones is awkward. Web versions require uploads, and desktop versions require opening a window first. Filee repackaged this old need with a "cursor donut" interaction that demos very well on camera. Then a free content distribution chain amplified it: Reddit cold start → Chinese and Korean software blogs and aggregator sites → GitHub Trending / HelloGitHub → AI-generated blogs, YouTube Shorts, Instagram Reels → media outlets like MakeUseOf. No paid promotion, no ad spend.

Growth data

Stars: repo created 2026-09-29. 2026-10-12 about 403 (the headline of Reveneau's coverage that day), 10-16 816,10-20 5,997,10-24 10,939,10-28 15,314,11-06 22,545 (our github database). GitHub API 11-06 reads 22,932, forks 1,369.
Largest single-day gains: 10-19→10-20 +2,280; 10-27→10-28 +2,445 (v2.2.0 released on 10-28; the same day "Everyone is a Product Manager" published a long article, and HelloGitHub also featured it).
Over the last 7 days +5,200, and in the 7 days before that +8,421. It's cooling, but still about 600–700 a day.
Real usage: installer downloads across 30 Releases total 723,629 (GitHub API, 2026-11-06). Downloads surged along with stars: v1.10.4 (10-15) 22k, v1.11.0 (10-17) 51k, v1.12.0 (10-19) 112k, v2.2.0 (10-28) 206k. v2.3.0 has been out for 3 days, with 42k Windows Setup downloads. There are also Microsoft Store and winget channels, whose numbers aren't public and aren't included above. The client prompts for updates, so some of the download count is existing users upgrading, so treat it only as an order of magnitude.
Release cadence: 9-29 through 11-03 saw 30 versions, nearly one a day. PRs contain Co-Authored-By lines, and the author also posted it to r/OnlyAICoding on Reddit (the post tag is "Something I Made With AI"), which shows AI-assisted rapid iteration.

Competitors

Name	Where	Launched	Scale	How it differs from Filee
Tichau/FileConverter	Open source / Windows	2015	15.6k star	Right-click menu only, no drag-and-drop radial menu; few formats, no HWP or Office document conversion
VERT	Open source / web (WASM)	2024-11	16.2k star	Converts locally in the browser; you have to open the site first
ConvertX	open source / self-hosted	2024-04	19.5k star	Self-hosted server required, aimed at technical users
Transmute	open source / self-hosted	2026-02	1.5k star	Same as above
CloudConvert / Convertio / FreeConvert / Smallpdf / iLovePDF	Web	Early on	100M+ monthly visits (unverified)	Requires uploading, with size limits and a paywall; Filee's pitch is literally "don't upload your contracts to shady websites"
Format Factory, HandBrake, Permute (paid on Mac)	Desktop	Early on	Big	You open a window, pick a format, hit start; most only handle audio and video
PowerToys (Image Resizer etc.), macOS Finder Quick Actions "Convert Image"	Big-company features	Early on	Built into the system	Only handles a handful of image formats
Korean HWP options: Ieum Office, Hancom Viewer, ONLYOFFICE	Desktop / web	Early on	Korean local	Can open HWP, but can't just drag a file and get a PDF/DOCX

Verdict: plenty of similar tools, Filee isn't short on competitors. It didn't invent "offline conversion"; what's new is the interaction, and it bundles a local must-have (HWP) with a huge range of formats into one free tool.

Where users come from (growth levers)

Reddit cold start (confirmed): 10-02 The author u/KnifeLemon_ posted in r/software (79 upvotes, 64 comments), the same day cross-posted to r/windowsapps and r/OnlyAICoding, and it was also shared to r/techiegeeks. The author wrote on Disquiet: "Recently people on Reddit who used it come back with their original files to report issues." Feature requests from Reddit users became PRs directly, e.g. #30 bundled engine.
Korean scene (confirmed): 10-06 The author posted an introduction on Disquiet (Korea's product community, similar to Product Hunt). 10-12 datanexus listed it, giting.kr 10-19 wrote an analysis, and people also recommended it organically on Naver blogs and Threads. The selling point: "convert HWP to PDF without Hancom."
Chinese software sites (confirmed, earliest and highest volume): 10-11 Keji Shi, 10-12 puresys released a portable version, 10-15 Xiaoyi and Diaoruanjian, 10-16 Tencent Cloud Developer Community, 10-17 Jianke.com, 10-18 two GitCode blog posts, 10-28 Rénrén Shì Chǎnpǐn Jīnglǐ ("gained nearly 14k stars"), plus Zhihu, Bilibili, OSCHINA and HelloGitHub coverage; 11-01 X post by @Gorden_Sun. The README has 17 languages, including Simplified and Traditional Chinese, so Chinese users face no barrier.
GitHub trending and ranking sites (likely): The README carries Trendshift badges for "C# weekly / daily #1" and a HelloGitHub badge; a Korean YouTube video title reads "깃허브 주간 9위" (GitHub weekly #9). Stars went up 1,700–2,300 per day from 10-19 to 10-21, consistent with landing on GitHub's global Trending. Our library only collects trending repos at least 60 days old, so trending_days_any=0 can't be used to rule this out.
AI content farms and short-video amplification (confirmed): Reveneau openly says it was "written by an AI system from the source code"; sites like airanks, frontiernow, devpik, indiekings, admin365, lockergnome and techwavearena batch-write about trending repos; YouTube Shorts has "1-minute analysis" channels in Japanese, Korean and English; Instagram has Reels; groups like githunt on Facebook are resharing it too. TikTok volume is small: the top one, @cubesites, has 46k views, and @jifryissadeen 14k views.
Press (confirmed, came late): German Netzwelt 10-27, MakeUseOf 11-03; by then the peak had already passed.
Product Hunt (didn't work): 10-10 launch, only 1 votes (our producthunt library). HN: Algolia search finds no Filee post.
Stores and package managers: Microsoft Store and winget are both listed, and the author even forked winget-pkgs to submit it. Counts as infrastructure; can't tell whether it drove traffic.

No paid promotion found.

Why it's working

The interaction is demoable: "Hold Ctrl and drag → a donut appears at the cursor → release to convert." A 27-second GIF explains it, which makes it a natural fit for short videos and README animations. Almost every article headline is about that "donut."
Anxiety about "uploading to shady sites": Netzwelt's headline asks "Upload your contract PDF to a shady online converter?" HN has also discussed free converter sites slipping malware into outputs. "Offline, zero telemetry" hits that nerve directly.
Broad format coverage: 180 → 263+ formats, one tool replacing a dozen small ones. MakeUseOf's headline is essentially "making the case for a dozen small apps harder to justify."
A local must-have opened the Korean door: Converting HWP/HWPX to PDF/DOCX without installing Hancom is a real pain point in Korea, and it gave the cold start a group of genuine users.
Multilingual + daily releases: 17+ README languages and 20 UI languages, so repost sites across China, Japan, Korea and Europe can use it as-is; a release almost every day, with Reddit and Issue feedback fixed the same day, keeps word of mouth rolling.
Automatic amplification from the AI content ecosystem: Once a repo hits trending, many AI blogs and Shorts channels follow up on their own, producing a second wave of traffic (10-24 to 10-30).

Differentiation

The core difference is that the conversion entry point lives at the cursor: no window to open, pick a format while dragging the file, and only formats that fit the file are shown. Other products either make you open a web page or a window, or, like Tichau, offer only a right-click menu.
The second difference is that it wrote its own DOCX/HWPX writer and doesn't depend on Office or Hancom; multi-step routes are planned automatically, e.g. HWP → HWPX → DOCX.
Are these differences why it took off? Yes, mainly the first one. Functionally it overlaps heavily with FileConverter and VERT, but almost everyone shares it for the donut GIF. "Offline, free, open source" is what makes people willing to install it; "the donut" is what makes them want to share it.

Reach and copycats

Visibility: widely discussed. 22.9k stars, 720k downloads. MakeUseOf, Netzwelt, Rénrén Shì Chǎnpǐn Jīnglǐ, HelloGitHub and Tencent Cloud have all written about it, and the Chinese X account @Gorden_Sun posted too. The product is entirely free, so no revenue can be disclosed.
Copycats have already appeared:
- OrbitDrop (i3sam, 10-18 repo built, 63 stars): a Windows version that pops a radial wheel on Shift, posted on r/foss with the title "I made a free app that converts files without opening anything."
- Tangerine (r/macapps, about 10-27): a paid Mac version using "drag + Shift" to convert; in the comments someone pasted a Filee link and others said "a bit pricey."
- The GitHub topic "browser-side file converter with a unique drag-and-drop format wheel" (the web version of the format wheel) has appeared.

What others can borrow

Take an old need (convert, compress, rename, remove background) and build a new interaction you can explain in one shot, then ship a README GIF.
Cold start on a must-have in a smaller-language market (here, HWP), and build out multilingual READMEs so repost sites in each country can cover it at zero cost.
Developers post and reply on Reddit themselves, ship releases daily, and treat user feedback as public iteration material.
Once on trending, AI content farms and Shorts channels amplify it automatically, so a wave of free traffic can be expected.
If you want to monetize, the Mac-side Tangerine is already testing paid. Filee itself doesn't charge; what's worth borrowing is its distribution playbook, not its business model.

Still unsure

Whether it reached GitHub's global Trending, and when (indirect evidence only).
Install counts from Microsoft Store and winget.
How many of the 720k downloads were upgrades; DAU and retention are unknown.
Whether the author will commercialize later (currently explicitly "no ads, no paid tier").
Which specific post or account ignited the 10-19 to 10-21 wave (Chinese sites, Korean YouTube or trending); no single source identified.

Sources

GitHub API: repos/KnifeLemon/Filee, releases (download counts), users/KnifeLemon (2026-11-06)
Our libraries: github repo_day (data card), producthunt post (Filee 2026-10-10,1 votes)
Reddit r/software: www.reddit.com/r/software/comments/1wvvhdn/ (Brave shows 2026-10-02,79 upvotes / 64 comments); r/windowsapps 1ww3wt6; r/OnlyAICoding 1ww41dn
Disquiet author post: disquiet.io/profiles/1RtvBem/posts
Reveneau 2026-10-12(403 star):reveneau.com/ainews/filee-open-source-file-converter-180-for…
Xiaoyi 10-15 xiaoyi.vc/filee.html; Tencent Cloud 10-16 cloud.tencent.com/developer/article/2762228; Rénrén Shì Chǎnpǐn Jīnglǐ 10-28 www.woshipm.com/ai/6485240.html; HelloGitHub hellogithub.com/repository/KnifeLemon/Filee; Zhihu zhuanlan.zhihu.com/p/2093972882120615924
X @Gorden_Sun (date inferred from tweet ID 2026-11-01): x.com/Gorden_Sun/status/2116770003781587395
Netzwelt 10-27 www.netzwelt.de/news/259962-... ;MakeUseOf 11-03 www.makeuseof.com/free-open-source-windows-file-converter-ap…
Trendshift trendshift.io/repositories/276987; Korean YouTube "깃허브 주간 9위" www.youtube.com/watch?v=8QcOIC45tOk
TikTok (TikHub search "filee"): @cubesites 46k views, @jifryissadeen 14k views
Copycats: OrbitDrop github.com/i3sam/OrbitDrop; Tangerine www.reddit.com/r/macapps/comments/1xalehy/
Competitor stars: Tichau/FileConverter, VERT-sh/VERT, C4illin/ConvertX, transmute-app/transmute (GitHub API 2026-11-06)

This article was written by AI from public data and the data we collect daily. Numbers are sourced, and inferences are labeled.