RunAnywhere (YC W26) – Faster AI Inference on Apple Silicon

Hi HN, we're Sanchit and Shubham (YC W26). We built a fast inference engine for Apple Silicon. LLMs, speech-to-text, text-to-speech – MetalRT beats llama.cpp, Apple's MLX, Ollama, and sherpa-onnx on every modality we tested. Custom Metal shaders, no framework overhead.Also, we've open-sourced RCLI, the fastest end-to-end voice AI pipeline on Apple Silicon. Mic to spoken response, entirely on-device. No cloud, no API keys.To get started: brew tap RunanywhereAI/rcli https://github.com/RunanywhereAI/RCLI.git brew install rcli rcli setup # downloads ~1 GB of models rcli # interactive mode with push-to-talk Or: curl -fsSL https://raw.githubusercontent.com/RunanywhereAI/RCLI/main/install.sh | bash The numbers (M4 Max, 64 GB, reproducible via `rcli bench`):LLM decode – 1.67x faster than llama.cpp, 1.19x faster than Apple MLX (same model files): - Qwen3-0.6B: 658 tok/s (vs mlx-lm 552, llama.cpp 295) - Qwen3-4B: 186 tok/s (vs mlx-lm 170, llama.cpp 87) - LFM2.5-1.2B: 570 tok/s (vs mlx-lm 509, llama.cpp 372) - Time-to-first-token: 6.6 msSTT – 70 seconds of audio transcribed in *101 ms*. That's 714x real-time. 4.6x faster than mlx-whisper.TTS – 178 ms synthesis. 2.8x faster than mlx-audio and sherpa-onnx.We built this because demoing on-device AI is easy but shipping it is brutal. Voice is the hardest test: you're chaining STT, LLM, and TTS sequentially, and if any stage is slow, the user feels it. Most teams fall back to cloud APIs not because local models are bad, but because local inference infrastructure is.The thing that's hard to solve is latency compounding. In a voice pipeline, you're stacking three models in sequence. If each adds 200ms, you're at 600ms before the user hears a word, and that feels broken. You can't optimize one stage and call it done. Every stage needs to be fast, on one device, with no network round-trip to hide behind

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FL score

82

out of 100

Verdict

BUILD

high confidence

Competition

8

competitors found, emerging market

Trend

1 community mentions

A technically superior AI inference engine for Apple Silicon that delivers breakthrough performance for on-device, multi-modal AI, with clear market demand but complex monetization for a solo builder.

The pain

Developers building on-device AI on Apple Silicon face significant latency issues, especially with chained models (e.g., voice AI), forcing them to compromise user experience, incur cloud API costs, or abandon local solutions due to slow inference infrastructure. Existing open-source tools often fall short on performance and specific optimizations.

The gap

While many tools exist for local AI inference, none consistently beat major competitors across LLM, STT, and TTS modalities with such significant speed gains on Apple Silicon. The unique technical approach (custom Metal shaders, no framework overhead) specifically addresses the 'latency compounding' issue in chained AI pipelines, creating a clear performance gap.

Build angle

Develop a core, highly optimized AI inference engine for Apple Silicon, capable of 1.5x-4.5x speed improvements over current leading solutions across various AI modalities. Offer this as an SDK or API for developers building on-device applications (e.g., voice assistants, real-time transcription, local LLM chat) where latency and privacy are critical. The open-source RCLI serves as a powerful demonstration and initial product.

Strengths

  • Addresses a significant and growing market need for faster, private, on-device AI.
  • Demonstrated technical superiority with impressive performance benchmarks.
  • Clear, measurable value proposition and specific pain points addressed.
  • Strong demand for local AI solutions to avoid cloud costs and privacy concerns.
  • Open-source RCLI provides strong initial validation and community engagement.

Risks

  • High technical complexity makes it challenging for a solo builder without deep low-level optimization expertise.
  • Monetization strategy for a core open-source inference engine is unclear and needs definition.
  • Highly competitive landscape with strong open-source incumbents (Apple MLX, llama.cpp, Ollama).
  • Risk of incumbents improving their performance to narrow the gap over time.
  • Requires continuous R&D to maintain performance advantage with new models and hardware.

Next steps

  1. Explicitly define a commercialization strategy beyond the open-source RCLI. How will the core engine be monetized for solo builders or small teams?
  2. Interview developers (especially those shipping on-device AI products) to validate willingness to pay for the performance gains, and for what type of packaging (e.g., licensed SDK, premium hosted service, managed models).
  3. Explore niche applications where the performance advantage is absolutely critical and where companies have budget (e.g., specialized voice AI in regulated industries, low-latency industrial automation).
  4. Consider bundling the engine with specific, high-value AI models as a 'pro' offering or a SaaS platform for easier deployment.

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