Support & FAQ

Install from the Chrome Web Store, then pin the MercariBoost icon to your Chrome toolbar so it's easy to reach. After install, log into Mercari in any tab (we'll detect your session automatically — we never see your password).

No. There's no MercariBoost account, no signup form, and no email collection. The extension works against your existing Mercari login — that's the only account involved.

Each permission is scoped to what the relist operation needs:

• storage — saves your listing data locally in your browser (never sent off-device)
• tabs + activeTab + scripting — needed to navigate between Mercari pages and inject the relist logic
• alarms — schedules the daily stale-listing check that updates the badge count
• sidePanel — lets you watch bulk relist progress without keeping the popup open
• debugger — required to interact with Mercari's React-based brand autocomplete and size picker; Mercari rejects synthetic events on those, so we use Chrome DevTools Protocol for real key/click events. Attached only during a relist, detached immediately after.
• host_permissions are restricted to www.mercari.com and Mercari's photo CDN (*.mercdn.net). The extension does nothing on any other site.

Relisting deletes your old listing and creates a fresh one with the same content (title, description, photos, price, category, brand, condition, shipping). The new listing gets a new Mercari item ID and goes to the top of search results, where buyers actually look.

This is the same workflow you'd do manually — Edit → Delete → New listing — just automated. The extension also handles photo caching so you don't lose images during the delete step.

A single relist takes 2–3 minutes. The extension intentionally uses randomized human-like delays between each step to avoid looking like automation. Bulk relisting 10 items takes about 25–35 minutes. Bulk relisting 50+ items can take a few hours — start it and let it run in the background.

Common practice among Mercari power-sellers is every 20–40 days per listing. The Stale-Listing Dashboard color-codes your listings by age (Fresh / Aging / Stale) so you can see at a glance which ones need attention. You don't need to relist daily — over-relisting just churns through the rate limit without buying more visibility.

Yes — the extension caps at 10 relists per hour as a self-imposed safety throttle, regardless of how many items you select. Going faster than that risks triggering Mercari's rate-limit / anti-automation systems. The throttle works in the background; you can queue 50 items and walk away, and the extension paces them automatically.

A few common reasons:

• Mercari's photo upload can be slow on listings with 8+ photos — wait 30 seconds before assuming it's stuck
• If you've recently relisted many items, the rate limiter is throttling subsequent ones
• If Mercari's site is slow (their backend has occasional latency spikes), each step takes longer

If a single relist takes more than 5 minutes with no progress in the side panel, something is wrong — see the troubleshooting FAQ below.

Honest answer: we can't guarantee they won't. Mercari's Terms of Service prohibit the use of automated tools, and they're within their rights to take action against accounts that use third-party automation.

The extension is designed to mimic natural human pacing (randomized delays, conservative intervals, no background scraping) to look as un-bot-like as possible. We've not seen reports of bans for typical usage patterns, but we can't make this risk zero.

Your account, your responsibility — see our Terms of Service §3 for the full disclosure.

No. The extension operates entirely within your browser — it never sees your password, never receives a session token, and never communicates with any server we control. All operations happen on the Mercari tabs that are already authenticated by you.

In your browser's local storage (chrome.storage.local), bound to your Chrome profile. Nothing is sent off-device. Uninstalling the extension permanently deletes all of it. See the full Privacy Policy.

The first time you open the popup, click Sync Listings to scrape your active Mercari listings. The sync takes 20–40 seconds depending on how many you have. If sync returns zero, make sure you're logged into Mercari in the same Chrome profile and try refreshing the Mercari tab before syncing again.

Probably not. The extension saves a recovery payload before deleting your original — so even if the new listing creation fails after the original was deleted, the listing data (title, description, photos, price, all of it) is still in storage and accessible from the popup's recovery banner. Click Retry to re-submit, or Dismiss if you'd rather post manually.

If you uninstall the extension before clicking Retry, the recovery data is lost — so resolve the banner before reinstalling.

This means the new listing didn't successfully post on Mercari's side. Common causes:

• Mercari flagged the price (too high, too low, banned keyword in title or description)
• Mercari's server hiccupped — try again
• A required field couldn't be filled because Mercari renamed the field testid (selector drift — usually fixed within 24h by us; check our drift issues)

The recovery payload above covers this case — your data is preserved.

Currently Chrome only. Edge should work because it's Chromium-based — try the unpacked install from the GitHub releases page. Firefox and Safari aren't supported; their extension APIs differ enough that we'd need a separate build, which isn't on the near-term roadmap.

That happens. Our automated drift watchdog runs every day and opens a GitHub issue the moment any selector breaks — we usually have a hotfix shipped within 24 hours. Check open drift issues on GitHub for current status, and update the extension when a new version ships.

Yes. No trial, no credit card, no signup. The free version is functionally complete — bulk relist, stale-listing dashboard, recovery safety net, all of it.

We may introduce a paid tier in the future with optional power-user features (scheduling, analytics, etc.) — but if and when that happens, the version you have installed continues to work at no cost for as long as we operate it. See Terms §1 for the commitment.

Chrome menu → Extensions → MercariBoost → Remove. All local data goes with it. Reinstalling later starts fresh; your Mercari listings re-sync from your account.

Email lesteroc15@gmail.com with as much detail as you can: what you were trying to do, what happened instead, Chrome version, and a screenshot if relevant. We reply within 24 hours.

For developers: you can also open issues on the extension's GitHub repo.