Capsule – Single-file web apps that save their data into SQLite
Hey HN,I always had the problem that building HTML pages is really simple now, but trying to save data required hosting it somewhere, and sharing it afterwards was not easy. Over the last few months, I've been building an app called Capsule (it’s also the file extension name) written in Rust with Tauri 2.0 that allows packing an HTML app and its data into a single SQLite file.The HTML file and any related assets are directly embedded in the database. User data can either be saved as a localStorage key/value store or via a MongoDB-inspired collections API as documents, saved in a table in the file. You can also save other assets, like PDF files or images, directly in the database to keep different documents together. All data can be easily exported to CSV or JSON if needed.Privacy and security were a big priority for me, so documents cannot do anything out of the box. They don’t have direct access to the file system and they require permission to access the internet. The permission model is still something I’m working to improve. Capsule documents can also use local or remote AI models for document specific AI features.One downside with this approach is that multiple people working on it will create different copies. To make it possible to merge different copies of the same file, each data entry has a unique UUID and timestamp.I’m planning to open up the file format specification for the 1.0 version of the app so other apps can read or write Capsule files.You can try it out in the web preview at https://withcapsule.app/preview with pre-built templates or use any AI provider of your choice to create a custom, Capsule-optimized app by using the following prompt:"Please read the app wizard instructions at https://withcapsule.app/prompt.txt and help me design an app.“I’m still working on the file format but there are migrations for each new version, so data should never be lost when using newer versions of the app in the futur
FL score
out of 100
Verdict
high confidence
Competition
No competitor data yet
Trend
No signal yet
A single-file app format that bundles HTML, assets, and data into SQLite for easy sharing and offline use, targeting developers who want to avoid hosting infrastructure.
The pain
The gap
Build angle
Strengths
- Solves a real friction point in the app development workflow that most developers have experienced.
- Privacy and security built in from the start, which is increasingly valuable.
- Open file format strategy removes lock-in and increases adoption potential.
- Rust and Tauri foundation is solid and performant.
- Merging capability via UUIDs and timestamps shows thoughtful design for multi-user scenarios.
- Works offline and requires no infrastructure, which is a genuine advantage over cloud-based alternatives.
Risks
- Market size is unclear. The target audience is developers building personal or internal tools, which is smaller than the total developer market.
- Free alternatives exist for most use cases. GitHub Pages is free for static sites, Vercel and Netlify are free for simple dynamic apps, and SQLite is already portable.
- Monetization path is not obvious. Charging for a developer tool requires clear value over free options, and the use case does not scream urgency.
- Adoption requires developers to learn a new format and workflow when they already have working solutions.
- Multi-user collaboration is limited by the file-based approach. The UUID merging strategy helps but is not as seamless as real-time collaboration tools.
- The permission model for internet access and file system access is still being worked out, which could be a blocker for some use cases.
- Distribution is unclear. How do users discover and share Capsule apps? There is no app store or marketplace mentioned.
Fly Labs Method
Is the pain real, is there a gap, is it the right time, can one person build it.
- Problem clarity
- 78
- Solution gap
- 75
- Willingness to pay
- 65
- Buildability
- 70
Real problem exists for developers wanting to share interactive HTML apps without hosting infrastructure, but willingness to pay is unclear since many alternatives exist and the use case is somewhat niche.
Value Equation
Dream outcome and how likely it feels, against the time and effort it costs.
The value delivery is clear for a specific segment, but the market size appears limited to solo developers and small teams building internal tools, making it hard to scale to a large business.
One-Person Business
Curiosity pull, identity fit, and a path from free value to paid for a solo creator.
The product solves a real friction point in the workflow of building and sharing web apps, but the target customer is not desperate enough to pay premium prices when free alternatives like GitHub Pages or Vercel exist.
Viral Frameworks
Hook strength, shareability, and how cheaply it can be tested.
The founder has built a working product with thoughtful design choices around privacy and data portability, but the business model and go-to-market strategy are underdeveloped.
Builder Lens
Evidence the problem exists, timing, defensibility, and a model that fits on a napkin.
This is a well-executed technical project that solves a real problem for a specific audience, but lacks the scale potential and clear monetization path that YC typically funds.
Five lenses, one composite. How scoring works
The angle
No market research recorded for this idea yet.
Semble – Code search for agents that uses 98% fewer tokens than grep
Hey HN! We (Stephan and Thomas) recently open-sourced Semble. We kept running into the same problem while using Claude Code on large codebases: when the agent can't find something directly, it falls back to grep, reading full files or launching subagents. This uses a lot of tokens, and often still misses the relevant code. There are existing tools for this, but they were either too slow to index on demand, needed API keys, or had poor retrieval quality.Semble is our solution for this. It combines static Model2Vec embeddings (using our latest static model: potion-code-16M) with BM25, fused via RRF and reranked with code-aware signals. Everything runs on CPU since there's no transformers involved. On our benchmark of ~1250 query/document pairs across 63 repos and 19 languages, it uses 98% fewer tokens than grep+read and reaches 99% of the retrieval quality of a 137M-parameter code-trained transformer, while being ~200x faster.Main features:- Token-efficient: 98% fewer tokens than grep+read- Fast: ~250ms to index a typical repo on our benchmark, ~1.5ms per query on CPU (very large repos may take longer)- Accurate: 0.854 NDCG@10, 99% of the best transformer setup we tested- MCP server: drop-in for Claude Code, Cursor, Codex, OpenCode- Zero config: no API keys, no GPU, no external servicesInstall in Claude Code with: claude mcp add semble -s user -- uvx --from "semble[mcp]" sembleOr check our README for other installation instructions, benchmarks, and methodology:Semble: https://github.com/MinishLab/sembleBenchmarks: https://github.com/MinishLab/semble/tree/main/benchmarksModel: https://huggingface.co/minishlab/potion-code-16MLet us know if you have any feedback or questions!
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Postgres extension for BM25 relevance-ranked full-text search
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Consus (YC F24) – LLM gateway for companies handling sensitive data
Hey Hacker News! I'm Eric, the founder of Consus. We route all AI requests to ITAR restricted and controlled unclassified information (CUI) compliant infrastructure. Consus itself satisfies ITAR restrictions, and we recently completed our FedRAMP equivalency audit against the 410 FedRAMP High controls. FedRAMP High is the U.S. government’s strictest security baseline for cloud services handling sensitive unclassified data. A breach of this data could cause severe or catastrophic harm. Achieving FedRAMP equivalency, or authorization, is required before processing CUI information.Demo: https://youtu.be/6MYxJe6P4oYAerospace and defense is experiencing rapid growth. Unfortunately, most companies are struggling to use AI because of necessary data protections & compliance risk. These companies can move even faster if they could use the AI tools that most other industries take for granted.I spent most of my career prior to Consus in aerospace & defense. I launched national security payloads at SpaceX, and was an early employee at Castelion. I’ve watched first hand how compliance red-tape makes it difficult for companies to adopt new technologies and trust vendors that touch their sensitive data. For example, I worked with a satellite manufacturer that doesn’t allow any AI tools, even for non-sensitive work.Even as AI has become extremely useful over the past 9-12 months, I was surprised by how many aerospace & defense companies refused to touch it. They could see how it could be helpful, but they were scared about model providers training on their data, violating an ITAR rule, or risk losing new business because of a failed cyber assessment. These are all rational fears.There were a lot of ways to solve some/all of these problems, but we focused on building a compliant AI inference layer that can "plug" into any AI tool or workflow. Just as OpenRouter integrates with most tools, Consus can connect to tools like ChatGPT or Clau
AI
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