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Feb 2026

Cocoon

A privacy-first Chrome extension that lowers sensory load online: it softens algorithmic feeds, reduces motion, and keeps a grounding exercise one click away. No accounts, no analytics, nothing leaves the device.

Live DemoView Source
Local only
Storage
Zero
Network calls
4 profiles
Presets
7 domains
Scoped hosts
Cocoon project visual

The constraint

Accessibility tooling for neurodivergent and mental-health needs is mostly built as a wellness product: an account, a subscription, and a dashboard that watches you. The people most helped by calmer browsing are the least well served by software that adds another surface to monitor.

The approach

A Manifest V3 extension where every adaptation is local and reversible. Profile presets (ADHD, Autism, Anxiety, Custom) set a baseline; feed cleaning, reduced motion, and color inversion adjust the page in place; scenario switches like Focus and Low stimulation expire on a timer and restore the baseline automatically.

Process
  1. 1
    Rationale before rules

    Wrote down the intent behind each preset first (docs/PROFILE_RATIONALE.md) so the defaults could be argued with rather than assumed.

  2. 2
    Domain-scoped hiding

    Kept feed rules in one typed module per domain instead of a global stylesheet, so a broken selector degrades on one site rather than everywhere.

  3. 3
    Fail loudly, not silently

    Added a banner that warns when a site's layout changes and the rules stop matching — a silent no-op is the worst outcome for an accessibility tool.

  4. 4
    Expiry as a first-class idea

    Built scenario timers on service-worker alarms so the baseline restores itself without the user having to remember what they changed.

Outcomes

  • Feed cleaning across seven platforms with three intensities and per-site overrides
  • Scenario modes that self-expire at 15/30/60 minutes so a temporary change never becomes permanent
  • Motion-free grounding overlay: guided breathing plus a 5-4-3-2-1 flow
  • Host permissions scoped to exactly the supported domains — no <all_urls>
What I'd do next
  • Ship the Chrome Web Store listing so installation stops requiring developer mode.
  • Add a Firefox build — the MV3 surface is close enough that most of the content script carries over.
  • Let presets be exported and shared, so an occupational therapist can hand someone a starting point.
Details

Built a Manifest V3 Chrome extension that reduces online overwhelm through feed cleaning, sensory controls, and a grounding overlay, with every setting stored locally via chrome.storage.local.

Designed scenario quick-switches (Focus, Low stimulation, Calm reset, Social guardrails) that expire on a user-chosen timer and automatically restore the baseline profile.

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