StemJSON
a language for LLMs to extend native mobile apps on the fly
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Hey HN! I'd like to share something I've been working on for a while and hear what you think. It's a new domain-specific language built on JSON and designed for AI, along with an ecosystem for building native mobile features, screens, and even entire apps quickly, right on the devices where they live. On top of that, end users can use AI to customize what their apps do on the fly, which might take the user experience to a whole new level.
HN · launched Sep 14, 2026 · 8 upvotes (top 50%) · 0 views
Niche: programming languages and interpreters · 161 launches, 2 in the last 7 days ▼ -75% · Explore this niche →
Category and tags
- Horizontal
- Dev tools
- Developer
- AI-native
- Commercial product
Visit website ↗ Source listing ↗
More like this: all 161 launches in programming languages and interpreters →
Could you build this?
Partial The declarative JSON schema and basic JSON-to-UI renderer can be built quickly, but a robust server-driven native UI runtime on iOS and Android supporting state, navigation, native events, and animations is a heavy mobile platform engineering challenge.
What it would actually take: The system requires an open declarative AST specification coupled with native runtime parsers and layout engines in Swift (SwiftUI) and Kotlin (Jetpack Compose). The hard part is building an isolated, bidirectional evaluation bridge for expressions, local state management, native event lifecycles, and secure sandboxing of dynamic code while complying with Apple App Store review guidelines on executable code. It demands experienced native mobile platform engineers.
Discussion
3 comments analyzed.
Concerns raised: Allowlist bottlenecks in SDUI payloads, Questionable advantage over existing serialization formats or free-form text
Competitors
Other products that read as similar to this one : 122 launches clear the similarity bar, closest 8 shown.
Attention rank: #59 of 123 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 317 days after the earliest competitor.
- StemJSON · ph · 2026-11-12 · 2 upvotes · similarity 0.74
- OpenUI · hn · 2026-03-11 · 8 upvotes · similarity 0.45
- SaiLang · ph · 2026-10-13 · 1 upvotes · similarity 0.44
- SIYAK · ph · 2026-11-05 · 1 upvotes · similarity 0.41
- Bible translated using LLMs from source Greek and Hebrew · hn · 2026-01-22 · 55 upvotes · similarity 0.40
- Why write code if the LLM can just do the thing? (web app experiment) · hn · 2025-11-01 · 436 upvotes · similarity 0.40
- deeplinkit · ph · 2026-10-31 · 2 upvotes · similarity 0.40
- Lefts · hn · 2026-08-07 · 6 upvotes · similarity 0.40
The niche, labels, vibe code rating and competitor comparison on this page are analysis by Nicheloom. If you use them, please credit nicheloom.com. How you may use our data.