Bluesky Report – #110

Video app Skylight is available for public release, with funding from Mark Cuban and 55k users in the first 24 hours. Spark is building their own entire video platform on ATProto, and just launched in beta.

Skylight and Spark

The main news this week comes from two video apps for Bluesky and ATProto, Skylight and Spark. Skylight is a video client for Bluesky, that has launched to the public this week. In the first 24 hours since launch, the app has gotten 55k users, and hit #2 in the entertainment category on the Apple App Store in the US. Skylight also announced that they’ve gotten a pre-seed funding round from Mark Cuban, as well as another venture fund. The total amount of funding is unknown. Cuban said he’d fund a TikTok alternative on ATProto in January this year, just before TikTok got banned in the US for a day. In 2 days TikTok is set to be banned again in the US. If that were to happen again, Skylight is now ready to welcome people looking for an alternative. The official Bluesky app has also made significant improvements to video in the meantime as well, potentially making the entire network more attractive as a TikTok alternative.

Spark is another video app for ATProto, and this week they launched in beta. Spark takes a different approach than Skylight, and is building their own entire platform that does not depend on Bluesky. They are building out their own infrastructure, including their own relay, appview, CDN and more. Spark also uses their own lexicon, allowing them to build their own network on ATProto.

On Lexicons

Spark and Skylight are taking two different approaches on building a video platform on ATProto, and the core difference is in how they approach ATProto lexicons. This difference is something we will likely be seeing more of on ATProto, so I think it’s worth diving deeper into the choices that both apps are making, and the tradeoffs that the choices entail.

A short and simplified explainer on lexicons: lexicons are a type of file structure for social data, and it says how data should be formatted. Every lexicon has an owner, usually the organisation who is building the app who uses the lexicon. It serves two purposes: it defines what an app can and cannot do, and it allows for interoperability between different apps. For example, the lexicon for a Bluesky post defines that a post should have a maximum length of 300 characters. Because this file structure is openly available, anyone else can also publish a Bluesky post. A lexicon says that if that post that is not made by Bluesky, but does follow the correct Bluesky lexicon, the post will show up in the Bluesky app. If it does not follow the lexicon correctly, it will not be visible.

Bluesky CTO Paul Frazee wrote some guidelines on lexicons this week, which says that you should use existing lexicons when you intend to interoperate with other apps, and if you don’t intend to interoperate you should create your own lexicon.

Skylight takes the first approach: the goal is to interoperate with Bluesky, and thus the app uses Bluesky lexicons. Effectively, Skylight is a client for Bluesky that focuses on only a portion of Bluesky posts, namely videos. This has some advantages for Skylight:

• Skylight does not have to do moderation. Every video posted via Skylight goes through Bluesky’s usual moderation infrastructure.
• Skylight inherits the 33M+ user base of Bluesky. When you open up Skylight, there is immediately a ton of videos to see.
• Skylight is not limited to only using Bluesky’s lexicon, and by integrating multiple types of lexicons Skylight can create an app that offers something different than just using the Bluesky app for video. Skylight CEO Tori White says that they are working together with stream.place to bring live streaming to the app. Stream.place is a live streaming platform with ATProto integration.

There are also downsides though:

• Skylight is fully dependent on Bluesky, for both moderation as well as operation.
• Skylight cannot change the limitations that Bluesky sets. Bluesky has set the length over videos at 3 minutes. This used to be one minute. Skylight has no control over these settings or when they are changed. Bluesky PBC could set the video duration limit to 10 minutes if they wanted to, without Skylight having any say in the matter.
• It is harder for Skylight to define its own culture. For example, US politics is one of the most dominant parts of the conversation on Bluesky. If someone is currently using Bluesky to mainly talk about US politics, they might be less interested in also having some silly meme videos get posted to their Bluesky profile. Skylight is already tweaking their algorithm to get more variation in their feeds due to the prominence of US politics videos.

Spark uses its own lexicon and infrastructure, and its upsides and downsides are mirrored to that of Skylight:

• Spark will have to do their own moderation for videos uploaded to Spark.
• Spark’s ecosystem for videos posted with the Spark lexicon will have to start from scratch.

There are also upsides:

• Spark can add features to videos that Bluesky does not have, Spark has talked about adding support to easily add music and other audio to your videos. Spark’s videos can also be of a higher quality (300mb vs 100mb) compared to Bluesky.
• Spark gets to create their own community and culture that is distinct from Bluesky’s culture.
• Spark is fully independent from Bluesky. Spark’s independence from Bluesky’s moderation is due to their choice in using their own lexicon, while the company also has made the choice to be fully independent in infrastructure: running their own relay, PDS, CDN and more.

The reason for spelling out the difference between these two approaches in detail is because Spark and Skylight will likely be the first of many more organisations that will have to make this choice between using other organisation’s lexicons and creating their own lexicons. There is no singular answer on which choice is better, and each comes with tradeoffs. Image-focused apps are another case where developers will make similar considerations about which lexicons they will be using. Flashes is a Bluesky client with an Instagram-like interface, that went for the first option, using Bluesky lexicons for posts. There has not been a major push yet towards an Instagram-like app on ATProto that uses its own lexicons and stays more separate from Bluesky. When people are considering building an image-focused app on ATProto, understanding the differences between Spark and Skylight might help with the tradeoffs and impact that come with each choice.

In Other News

Altmetric has posted a blog with more details on their finding that Bluesky now has more posts on academic research published in 2025 than X has. What stands out to me is that Bluesky has a considerably larger ratio of original posts discussing research, compared to X. In contrast, X’s posts on research trend much more towards reposts. Altmetric also reports a finding I have not seen anywhere else yet, namely that Bluesky tends to be more active on weekdays, whereas X tends to be busier during weekends.

Bluesky PBC is growing; the company currently has around 20 employees and is hiring for 6 new positions. The company recently hired a product designer, and is now looking for a Head of Product as well.

Custom feed builder Graze has released a tool, Contrails, to turn their custom feeds into a developer-friendly structure that allows the feed to be used for other purposes than reading the posts via the Bluesky app. For example, when building a bot that listens to certain keywords and then take an action, bots developers usually listen to the firehose of the entire network. With Contrails, Graze can do the filtering, and developers can use this filtered stream of output to build their own toolings, such as bots, dashboards or moderation systems.

A sprawling blog post by Blacksky founder Rudy Fraser, about building an internet of many autonomous communities. There are many ideas in the post, and I can recommend reading it in full. I want to highlight a small section, where Fraser lists some things that are needed for building communities:

• Treat “communities” as first class citizens (like “users” or “customers”). This is like how labelers are a special kind of account. Allow people to build things specifically for community account types.
• Trust that individuals will show up to shoulder the burden of forming and maintaining these communities (incl. but not limited to performing moderation responsibilities – some of us are weird like that). This means as new features are designed, you don’t need to ask “but who will do that”? Probably me tbqh.
• At best provide a non-extractive/non-taxing monetization path (DID2DID payments?) and at least don’t get in the way of communities forming reciprocal or gift economies.

Treating communities as a specific type of entity within the ATProto network makes sense to me. Both Blacksky and Northsky are creating spaces within ATProto and Bluesky. Blacksky is already successful at creating a vibrant community, and Northsky looks to do the same as well. Other communities are likely to follow suit to build their own places on ATProto. This might just expand beyond Bluesky-type communities, see for example how video apps like Spark have the potential to build a video-first community that is apart from Bluesky and microblogging, while also being connected to it. One of the core ideas of the fediverse is that make up of an interconnected network of many independent communities. While the vision of interconnected communities is one of the most appealing part of the fediverse to me, it struggles to make the switch from ‘connected servers’ to ‘connected communities’.

The Links

In the media:

• New Paradigms in Trust and Safety: Navigating Defederation on Decentralized Social Media Platforms – Carnegie Endowment for International Peace.
• Can Bluesky’s AT Protocol build the decentralized social media ecosystem the Fediverse aspires to? – Joshua Benton/NiemanLab
• Blue Skies Ahead: Social Media’s Quiet User Revolution – Damion Taylor/Forbes
• Beyond Bluesky: These are the apps building social experiences on the AT Protocol – Sarah Perez/TechCrunch

And some more links:

• Hose race is a silly race game that allows you race words against each other directly from the Bluesky firehose (accompanying blog post here).
• A writeup of the recent ATmosphere Conference in Seattle by one of the organisers.

That’s all for this week, thanks for reading! If you want more analysis, you can subscribe to my newsletter. Every week you get an update with all this week’s articles, as well as extra analysis not published anywhere else. You can subscribe below, and follow this blog @fediversereport.com and my personal account @laurenshof.online on Bluesky.

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