StemJSON
a language for LLMs to extend native mobile apps on the fly
Details
- External ID
- 49695057
- Source
- HN
- Company
- —
- Product
- StemJSON
- Website domain
- stemjson.com
- Launched
- Sept. 14, 2026
- Cohort
- —
- Upvotes
- 8
- Upvotes percentile
- 0.5015948963317385
- Tags
- —
- Fetched at
- Sept. 18, 2026, 5:02 p.m.
- Updated at
- Sept. 18, 2026, 5:02 p.m.
Description
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.
Enrichment
- Theme
- Vertical
- Horizontal
- Function
- Dev tools
- Audience
- Developer
- AI stance
- AI feature
- Project type
- Hobby / open-source project
- Normalized one-liner
- json schema language for llms to modify mobile apps
- Manually corrected
- False
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 — 53 launches clear the similarity bar, closest 8 shown.
Attention rank: #29 of 54 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 317 days after the earliest competitor.
- OpenUI · hn · 2026-03-11 · 8 upvotes · similarity 0.44
- Bible translated using LLMs from source Greek and Hebrew · hn · 2026-01-22 · 55 upvotes · similarity 0.39
- Lefts · hn · 2026-08-07 · 6 upvotes · similarity 0.38
- Why write code if the LLM can just do the thing? (web app experiment) · hn · 2025-11-01 · 436 upvotes · similarity 0.38
- Modelence Mobile Builder · ph · 2026-07-01 · 214 upvotes · similarity 0.38
- Veap · ph · 2026-09-22 · 2 upvotes · similarity 0.37
- Nor Abon · ph · 2026-09-19 · 4 upvotes · similarity 0.37
- LLM Ⅰ beta · ph · 2026-09-15 · 1 upvotes · similarity 0.36
Other launches for this product
- No other launches for this product.
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