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Kirill Osenkov

@kirillosenkov.com
1.5K followers 272 following 790 posts

(Unofficial) VP of Developer Productivity at Microsoft. Developer tools, engineering systems, .NET, C#, Roslyn, Visual Studio, Editor, WPF, Avalonia, MSBuild.

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Kirill Osenkov @kirillosenkov.com · 3h
I've been in the geometry business for 27 years. I just reconstructed the timeline of working on it since 1999: livegeometry.com/history
A History

Twenty-seven years of ruler and compass: from a Visual Basic program in Kharkiv to a WebAssembly app in the browser, by way of two false starts and one long silence.

A program begins in Kharkiv
Kirill Osenkov starts DG at the Kharkiv pedagogical university in Ukraine, under the supervision of Sergey A. Rakov. The language is Visual Basic 6.
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Kevin Gosse @kevingosse.net · 20h
I published a new article: the hidden trap of fixed buffers in C#. It explains a quirk of fixed buffers that could easily bite you, if you're one of the few people who still have to use that feature. minidump.net/the-hidden-t...
minidump.net
The hidden trap of fixed buffers in C#
After all, if they’re marked as unsafe, there’s gotta be a reason, right?
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Sebastian Lague @sebastianlague.bsky.social · 20h
hey, looks really cool! :)
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Kirill Osenkov @kirillosenkov.com · 28/09/2026
A eulogy for the software engineer davekiss.com/blog/eulogy-... by @davekiss.com
davekiss.com
A eulogy for the software engineer | Dave Kiss
Dearly beloved, we are gathered here today to bury the software engineer, along with a pair of headphones, a notebook, and a keyboard. A talk about what went in the ground, and what's still in your ha...
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Matt Keeter @mattkeeter.com · 28/09/2026
hi friends I'm very excited to announce Halfspace, my experimental cross-platform IDE for solid modeling with distance fields! This has been in progress since midway through last year, and it's finally "done enough" to make it more public.
mattkeeter.com
Halfspace
An IDE for solid modelling with distance fields
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Xogot: Godot on iPad and iPhone @xogot.bsky.social · 28/09/2026
We just announced Xogot Modeler. Inspired by Unity’s ProBuilder, it lets you build levels in your 3D Godot scenes. Create geometry, extrude meshes and more without leaving Xogot. Check out @migueldeicaza.bsky.social's blog post for the full story, with lots of demos: blog.xogot.com/xogot-modeler/
blog.xogot.com
Xogot Modeler
Earlier this year we introduced the Asset Placer and the Asset Browser, and today we are introducing the Xogot Modeler. This tool helps you prototype levels easily from within the editor, without hav...
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BetaKit @betakit.com · 24/09/2026
Devolutions, one of the biggest tech players in the small Québec town of Lavaltrie, is getting into the corporate VC game.
betakit.com
Devolutions wants to support Québec’s IT ecosystem with corporate venture capital | BetaKit
IT services firm has already invested $10 million CAD in tech firms through its new venture division.
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Kirill Osenkov @kirillosenkov.com · 24/09/2026
Announcing Live Geometry: livegeometry.com Try it out especially if you have geometry-aged kids. Built using @avaloniaui.net
Live Geometry logo, New Drawing button and 6 tiles with various drawings: Continuous deformations, Bubbles, Pythagorean Theorem, Circumscribed circle, Inscribed Circle, Morley's Miracle
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Kirill Osenkov @kirillosenkov.com · 23/09/2026
Hope no one catches me typing "anal" into the address bar when I navigate to Google Analytics
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Miguel de Icaza @migueldeicaza.bsky.social · 22/09/2026
I know many of you woke up this morning hoping, "I wish I could have a terminal emulator as comprehensive as Ghostty, but with a settings panel and powered by Swift without compromising on the speed?" I got you fam: github.com/migueldeicaz...
github.com
Releases · migueldeicaza/tecolot
My terminal app based on SwiftTerm. Contribute to migueldeicaza/tecolot development by creating an account on GitHub.
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Gérald Barré @meziantou.net · 22/09/2026
Using JsonPath with System.Text.Json to query JSON in .NET #dotnet #json www.meziantou.net/using-jsonpath-wi…
meziantou.net
Using JsonPath with System.Text.Json to query JSON in .NET - Gérald Barré
Learn how to use Meziantou.Framework.JsonPath to evaluate RFC 9535 JSONPath expressions against System.Text.Json documents in .NET.
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Marc-André Moreau @awakecoding.com · 22/09/2026
Devolutions Terminal, in the browser, using Avalonia 👇
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andrew blinn @disconcision.com · 21/09/2026
introducing the embodied coding agent canvas I've been working on, and how it integrates with per-data-type GUI generation to support more transparent type-directed agent dev processes. remote demo for ARIA SGAI www.youtube.com/watch?v=U6lY...
youtube.com
Hazel constellation canvas demo
YouTube video by andrew blinn
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Jan K. ™ #T1D 🍚🩸 #OSS #MVP #FCKNZS @punker76.bsky.social · 20/09/2026
They keep telling us #WPF is dead. I built something new anyway: the MahApps.Metro Gallery. Yes, it is "just" a demo app. But hey ;-) it's made with ❤️ github.com/MahApps/MahA... #dotnet #MahApps #ControlzEx
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Sean Killeen @seankilleen.com · 20/09/2026
An easy decision this week: our team handily voted to keep and pay the OSMF for @simoncropp.bsky.social's Verify .NET. Verify is a snapshot testing tool/ecosystem and it's great. Here's how it went down: #dotnet #oss #osmf
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Jan K. ™ #T1D 🍚🩸 #OSS #MVP #FCKNZS @punker76.bsky.social · 17/09/2026
MahApps.Metro. Remember that? I'm working on it again. Yes, old #WPF. Also the thing a lot of desktop apps are still written in, and those could stand to look a little less like 2012. Three style sets now. Pick one, swap a line in App.xaml, done. #MahApps #ControlzEx #XAML #dotnet
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Gérald Barré @meziantou.net · 15/09/2026
XPath for custom types in .NET #dotnet #xml www.meziantou.net/xpath-for-custom-…
meziantou.net
XPath for custom types in .NET - Gérald Barré
Learn how to implement XPath queries for custom non-XML types in .NET, enabling users to search complex object hierarchies with a simple query language.
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Jonathan Pobst @jpobst.com · 08/09/2026
Been working on rewriting Pinta in Avalonia/Skia: paintium.app. @avaloniaui.net has come so far and has really matured into a first class application framework!
paintium.app
Paintium - Easy Paint Program & Image Editor for Windows
An easy, modern paint and image editor with layers, blend modes, 46 effects, precision selections, and unlimited undo.
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Quantian @quantian.bsky.social · 08/09/2026
Dancing very very VERY close to saying “OpenAI stole our almost-complete proof of Navier-Stokes from internal access to our ChatGPT sessions because they were desperate to scoop Anthropic” which is absolutely 100% a believable thing OpenAI would do right now cims.nyu.edu/~tristanb/st...
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Sebastien Ros @sebastienros.me · 07/09/2026
The feedz.io package repository is the best one I have used so far. Super fast, ample free usage, intuitive UI. A pushed package appears and is available in seconds.
feedz.io
feedz.io — Private package hosting
Host private NuGet, npm, and Chocolatey packages with generous storage limits and no per-seat pricing. Simple, flat-rate plans.
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Kirill Osenkov @kirillosenkov.com · 07/09/2026
I hope someone is taking a serious new look at the Voynich manuscript with Fable or Astra
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andrew blinn @disconcision.com · 06/09/2026
structured editing unplugged
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Christophe Nasarre @chrisnas.bsky.social · 05/09/2026
I'm starting a new series about internals of AI harnesses such as Cursor, Claude or Copilot. Let's start with Cursor that I use everyday chrisnas.github.io/posts/2026-0...
chrisnas.github.io
Spying on Cursor: agent hooks, payloads and a simple observer
How I used Cursor agent hooks to observe prompts, thoughts, tool calls, MCP executions, file edits and subagents without changing the agent's behavior.
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Javier Suárez @jsuarezruiz.bsky.social · 04/09/2026
Nova.Avalonia.UI is now available on NuGet! www.nuget.org/packages/Nov... The gallery has also been updated, along with the documentation and examples. Everything is now ready to explore and use. #avalonia #dotnet
Controls catalog for Nova.Avalonia.UI with a left sidebar listing control names and a main area showing the title and description, tag pills (including "27 samples" and "Light and dark"), and rounded cards for controls like Avatar, Badge, and BarcodeGenerator.
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Kirill Osenkov @kirillosenkov.com · 04/09/2026
Stampeded! from the @ilspy.bsky.social team is a new intelligent code review tool with semantic navigation: www.youtube.com/watch?v=r16Y... github.com/icsharpcode/...
screenshot of a code review tool with changed files tree in the top left, repository tree in the bottom left and the diff/editor in the right pane (light theme). Showing the ILSpy codebase.
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Eric Lippert @ericlippert.com · 04/09/2026
After many delays, my book is finally done! Print copies ship on September 29th, and the e-book is HALF OFF at www.manning.com/books/fabulo... from now through Labor Day, WHAT A FABULOUS DEAL! Thanks to everyone who supported this project; I appreciate you all so much.
manning.com
Fabulous Adventures in Data Structures and Algorithms - Eric Lippert
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Avalonia UI @avaloniaui.net · 02/09/2026
Hot Reload for Avalonia is here 🔥 Edit your XAML or C#, and see the changes immediately in your running app. No restart. No renavigation. Support for Windows, macOS, Linux, iOS and Android. avaloniaui.net/blog/hot-re...
avaloniaui.net
Hot Reload for Avalonia - Avalonia UI Blog
Avalonia Hot Reload is here: edit XAML and C#, see it live, no restart, on desktop and mobile.
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Marc-André Moreau @awakecoding.com · 01/09/2026
Here's Windows Terminal in C# and Avalonia instead of C++ and WinUI. Next steps would be Ghostty and cross-platform support 👇
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Peter Ritchie @peterritchie.com · 02/09/2026
Hey, Fabulous Adventures in Data Structures and Algorithms by @ericlippert.com was published today! www.manning.com/books/fabulo...
manning.com
Fabulous Adventures in Data Structures and Algorithms - Eric Lippert
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Gérald Barré @meziantou.net · 01/09/2026
Generate and review the public API of a .NET library #NuGet #dotnet www.meziantou.net/generate-and-revi…
meziantou.net
Generate and review the public API of a .NET library - Gérald Barré
Generate and review the public API of .NET libraries in pull requests to catch breaking changes before publishing a NuGet package.
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Andrew Lock "Sock" @andrewlock.bsky.social · 01/09/2026
Blogged: The pain of serializing unions and closed class hierarchies with System.Text.Json in .NET 11 andrewlock.net/exploring-th... In this post I discuss the System.Text.Json support for unions and closed hierarchies coming in .NET 11, the decisions made and some of the sharp edges I hit #dotnet
andrewlock.net
The pain of serializing unions and closed class hierarchies with System.Text.Json: Exploring the .NET 11 preview - Part 7
In this post I discuss the System.Text.Json support for unions and closed hierarchies coming in .NET 11, the decisions made, and some of the sharp edges I hit
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Vlád Zä @vlz.bsky.social · 29/11/2024
Did you know, that compiler explorer can do #dotnet? It can do JIT, Crossgen2, ILDasm and ILSpy? You can even compare codegen for different compiler versions, how cool is that? godbolt.org/z/9EWhYbfv4
godbolt.org
Compiler Explorer - F#
module Program let square x = x * x
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CBS Detroit @cbsdetroit.bsky.social · 31/08/2026
NASA's $4.3 billion Roman Space Telescope was launched atop a SpaceX Falcon Heavy rocket Sunday, kicking off a three-month voyage to a point in space a million miles from Earth where it will map the large-scale structure of the cosmos with a wide-field 300-megapixel camera.
cbsnews.com
NASA launches its Roman Space Telescope to explore the hidden universe
NASA's Roman Space Telescope​ launched shortly after daybreak from Kennedy Space Center and blazed toward an observation point 1 million miles away.
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Kirill Osenkov @kirillosenkov.com · 29/08/2026
GitHub recently changed the color for the C# language from green to the slate blue .NET uses #7355DD and I just can't get used to it. C# was always green, VB was always blue. I get what they were going for but I dunno.
four bars: Visual C# 2008 Express Edition (green), Visual Basic is blue, C++ is orange-ish and Visual Web Developer is purple-ish
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Kirill Osenkov @kirillosenkov.com · 28/08/2026
Lunar eclipse is visible now in Seattle area, look east
Moon above trees with lower half obscured by Earth shadow
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andrew blinn @disconcision.com · 26/08/2026
modules are metaballs
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Kirill Osenkov @kirillosenkov.com · 26/08/2026
ILSpy working in a browser: osenkov.com/ilspy Powered by @ilspy.bsky.social and @avaloniaui.net
Screenshot of a browser tab and ILSpy UI in it: tree with ICSharpCode.Decompiler assembly on the left, with namespaces and types, decompiled assembly attributes in a yellow text editor on the right
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Quanta Magazine @quantamagazine.org · 24/08/2026
How many lines lie on a cubic surface? (The answer is 27.) A statement that’s been known for nearly 180 years has recently gained fresh nuance and relevance. www.quantamagazine.org/new-math-rev…
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Kirill Osenkov @kirillosenkov.com · 22/08/2026
I bought Radical Pie and played with it, and it's delightful It must have been such a blast to work on @disconcision.com @neurocy.bsky.social have you seen this?
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Kirill Osenkov @kirillosenkov.com · 22/08/2026
it only recently dawned on me that Claude must have been named after Claude Shannon
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Kirill Osenkov @kirillosenkov.com · 21/08/2026
People who make decisions don't feel the pain, and people who feel the pain don't make decisions
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Eric Lengyel @ericlengyel.bsky.social · 10/07/2026
Do you use the equation editor built into Microsoft Word? If so, you can put an end to your suffering by upgrading to Radical Pie. radicalpie.com
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Morten Nielsen @dotmorten.xaml.dev · 17/08/2026
I'm excited to share that today is my first day at Microsoft, joining the Windows Developer Platform team! I'll be working on the Windows App SDK and working with developer communities to help evolve the platform and make building great apps on and for Windows even better. #winui
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Jeremy D. Miller (The Shade Tree Developer) @jeremydmiller.bsky.social · 14/08/2026
It would be nice to have some place for .NET devs to chat that isn't as unpleasant as the main dotnet reddit: www.reddit.com/r/moderndotn... Just started this week by the Akka.Net folks
reddit.com
moderndotnet
Discussions and projects for .NET and any supported CLR language (C#, F#, and more)
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Marc-André Moreau @awakecoding.com · 14/08/2026
Introducing Devolutions Ahtola, an experimental port of Turso's SQLite-compatible database engine from Rust to pure C# 🚀 No native SQLite library - the whole engine is NativeAOT-compatible .NET managed code ⚡️ Oh, and there's even a PowerShell module! 👇 github.com/Devolutions/...
github.com
GitHub - Devolutions/ahtola: An experimental C# port of Turso’s SQLite-compatible database engine
An experimental C# port of Turso’s SQLite-compatible database engine - Devolutions/ahtola
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ILSpy - .NET Decompiler @ilspy.bsky.social · 12/08/2026
About a month after the last 10.x servicing release comes #ILSpy 11. Ported to @avaloniaui.net, now available for Linux, Mac and Windows! THE open-source #dotnet decompiler just got ways more useful, read about the three major areas of investment at github.com/icsharpcode/...
github.com
Release ILSpy 11.0 · icsharpcode/ILSpy
The major news item of this release cycle is us porting ILSpy from WPF to Avalonia. With this port, ILSpy is now available on Linux and Mac in addition to Windows. Do note that there is no longer a...
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Miguel de Icaza @migueldeicaza.bsky.social · 11/08/2026
Because users of RTL languages deserve an iOS terminal app that doesn’t render Arabic and Hebrew like a botched plastic-surgery makeover, La Terminal 2.0.4 is now on the App Store—with full BiDi support. apps.apple.com/us/app/la-te...
apps.apple.com
La Terminal: Mosh & SSH Client App - App Store
Download La Terminal: Mosh & SSH Client by Xibbon, Inc on the App Store. See screenshots, ratings and reviews, user tips, and more apps like La Terminal: Mosh &…
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Kirill Osenkov @kirillosenkov.com · 11/08/2026
Honest caveat: This is not em-dash. This is watermarking.
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Chet Husk @chethusk.bsky.social · 11/08/2026
3) MSBuild's Multithreaded mode is freaking awesome now! We've made many core Tasks multithread-safe, so most common project types see a _good_ speedup on 'cold' builds and a _really good_ speedup on 'warm' builds. There are plenty more Tasks to go, but now is the time to try it out!
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