Last updated October 13, 2026
These terms are the agreement between you and Backline when you use it to run your shop. The short version: you own your data, you decide what Backline does on your marketplaces, and Backline does its best to keep your listings in step but cannot promise a marketplace will always answer.
Backline is operated by To decide: legal entity name, a To decide: state and type of entity, e.g. Texas limited liability company ("Backline", "we"). You can reach us at support@backlinesync.com.
"You" means the person who signs up and the shop (the organization) they create or join. If you sign up for a business, you are agreeing on its behalf and confirming you are allowed to.
Backline helps used and vintage gear sellers keep one inventory in step across the marketplaces they sell on. Depending on your plan and what you connect, it can:
You need an account to use Backline, and you are responsible for what happens under it: keep your sign-in safe, and only invite people to your shop you trust to act for it. Owners and admins can change listings, settings and connections; anyone you invite can see your shop's records.
When you connect a marketplace you authorize Backline to act on your behalf there, within the access you grant: to read your listings and orders, and to create, change and end listings and upload photos. You confirm you are entitled to give that access.
Backline is not affiliated with, endorsed by or sponsored by Reverb, eBay, Shopify, Sweetwater or any other marketplace. Each marketplace has its own terms, fees and rules, and you remain responsible for following them — including what you list, how you describe it, and how you ship it. A marketplace can change or withdraw the access Backline relies on at any time, and some features may stop working if it does.
Backline checks your listings every fifteen minutes and, where a marketplace tells it about a sale, acts within seconds. How quickly a sale is noticed depends on the marketplace: some notify straight away, and others Backline has to ask, which can take up to an hour.
That narrows the window in which an item can sell twice; it does not close it. Marketplaces have outages, refuse changes, and rate-limit requests, and a sale can happen in the gap. Keep an eye on your listings and the activity feed, which records what Backline did and anything it could not do.
Backline is not responsible for a marketplace being unavailable, for a listing a marketplace refuses or removes, or for a sale made before a takedown reached every marketplace.
Backline has a Free plan and a paid Pro plan. A new shop gets a 7-day trial of Pro with no card required. If you add a card during the trial, Pro carries on and the first charge is made on the day the trial ends; if you do not, the shop moves to the Free plan.
Pro is billed monthly in advance, through Stripe, until you cancel. Prices are shown on the pricing page and do not include any sales tax that applies. We will give you at least 30 days' notice before a price change affects your subscription.
When a trial ends without a card, or a paid plan is cancelled or cannot be collected, Backline stops listing and updating. For 30 days after that it still takes a listing down everywhere when it sells anywhere, so nothing sells twice while you decide. After that it stops acting on your marketplaces altogether.
At any point once your plan has ended you can ask Backline, from the billing page, to take down every listing it is keeping in step on your other marketplaces. Your records stay in Backline either way.
You can cancel at any time from the billing page. Cancelling stops the next charge; Pro stays on until the end of the period you have paid for. Refunds are covered by the refund policy.
Your shop's records are yours. You give us permission to store and process them only to provide Backline to you, as described in the privacy policy. We do not sell your data or your buyers' data.
Do not use Backline to list anything you are not allowed to sell, to misdescribe an item, or to break a marketplace's rules or the law. Do not try to get into another shop's data, overload or disrupt the service, or copy or reverse-engineer it. We may suspend a shop that does, and will tell you why where we can.
Backline will change as marketplaces change. We may update these terms; if a change matters, we will tell you by email or in the app before it takes effect. Carrying on using Backline after that means you accept the new terms.
You can stop using Backline whenever you like. We may end or suspend your access if you break these terms, or if we stop offering Backline, with notice where we can give it — and in either case you will be able to take your records with you.
Backline is provided as it is and as available. To the extent the law allows, we make no promise that it will be uninterrupted or free of errors, or that a marketplace will accept every change.
To the extent the law allows, we are not liable for indirect or consequential losses, including lost sales or lost profits, and our total liability for any claim is limited to To decide: the cap, e.g. the fees you paid in the 12 months before the claim.
These terms are governed by the laws of To decide: state, and any dispute will be resolved in the courts of To decide: county and state.
Questions about these terms: support@backlinesync.com.