Filament Labs

Independent software · Fayetteville, Arkansas

Tools that leave room for judgment

Filament Labs builds focused software for people who want the underlying signal, durable control over the work, and an honest account of what the tool can know.

Explore the work
01 Show the signal Health data without a manufactured verdict.
02 Preserve the state Local work that survives the active conversation.
03 State the limits Specific tools, plain claims, no mystery layer.

Selected work · 2026

Four instruments,
one posture

The surfaces are different: an Apple Watch face, an iPhone, a long-running local process, a usage signal inside Codex. What they share is easier to show than to say.

Raw heart-rate variability

hrv/spark

A clear view of HealthKit SDNN values across useful time windows—without readiness scores, stress labels, or an interpretation layer.

  • iPhone + Apple Watch
  • No account
  • No telemetry
Explore HRVSpark App Store ↗
HRVSpark shown on an Apple Watch Ultra-style case with HRV gauge and sparkline complications HRVSpark raw HRV data shown on an iPhone Signal, not score.

Transparent resting heart rate

rhr/spark

Sedentary heart-rate trends and Apple’s daily resting heart rate, clearly labeled and never blended into a mystery metric.

  • iPhone + Apple Watch
  • Two named sources
  • One-time purchase
Explore RHRSpark App Store ↗
RHRSpark shown on an Apple Watch Ultra-style case with resting heart-rate complications RHRSpark resting heart-rate data shown on an iPhone Two sources. Clearly named.

Open-source Codex plugin

Codex
Process Jobs

Durable detached local process jobs for builds, tests, evaluations, and finite work that should not monopolize an active Codex turn.

  • macOS + Linux
  • Local execution
  • Apache-2.0
Explore CPJ GitHub ↗
Before and after Codex screenshots comparing repeated foreground polling with a detached CPJ job View full size ↗ Codex Process Jobs icon
Release the conversation. Keep the work.

Open-source Codex plugin

Codex
Usage &
Resets

Your current distance from Linear Pace, translated into practical advice for the work ahead.

  • Read-only + local
  • No telemetry
  • Apache-2.0
Explore CUAR GitHub ↗
Actual Codex usage moving above and below a straight Linear Pace reference, with a dashed Projected Exhaustion estimate continuing past Now
Know your usage pace. Let Codex advise.

Working principles

Respect is a product decision.

Each one costs a feature. That is how you can tell they are real.

  1. 01

    Show source material.

    HRVSpark ships raw SDNN values and no readiness score—the interpretation layer that would be easiest to sell is the layer it leaves out.

  2. 02

    Keep control close.

    Codex Process Jobs names its limits up front—finite work, local execution, not a hosted runner—so the capability stops where the machine does.

  3. 03

    Name the boundary.

    CUAR observes Unscheduled Resets cautiously from evidence and refuses to predict them. A confident forecast would demo better; it would also be a guess.

The studio

Independent by design.
Small on purpose.

Filament Labs is the independent work of Joel Farthing in Fayetteville, Arkansas: health instruments, developer utilities, and the occasional project that earns its own visual language—Blackberry Hollow, Ethan Farthing.

The common thread is not a category. It is software that respects the intelligence, time, and attention of the person using it.

Email Filament Labs info@filamentlabs.io