What Is Seam? The Smart Lock API Airbnb Hosts Need to Know About

If you have ever tried to automate anything with your smart locks beyond what Airbnb's native integration offers, you quickly run into a wall. August has its own API. Schlage has a different one. Yale has a third. They do not speak the same language, and most of them require expensive enterprise agreements just to get started.

Seam was built to fix exactly this problem. It is the smart lock API platform that AirMultiLocks is built on — and understanding how it works will help you understand why multi-door lock automation is now possible for individual hosts, not just large property management companies.

What Is Seam?

Seam (seam.co) is a unified API for smart locks and access control devices. Instead of writing separate code for each lock brand, developers connect once to Seam and can control any supported device through a single, consistent interface.

Think of it as a translator that sits between your app and your hardware. When AirMultiLocks tells Seam "add access code 4821 to this lock," Seam handles the brand-specific details — whether that lock is an August Connect, a Schlage Encode, a Yale Assure, or any of the 100+ other supported devices. The app only needs to speak Seam's language.

The Fragmented Smart Lock Ecosystem

The smart lock market today looks a lot like the early smartphone market — a dozen competing platforms, none of which talk to each other. August uses Bluetooth and Wi-Fi with its own cloud. Schlage uses Z-Wave. Yale has its own hub system. Kwikset uses its SmartKey ecosystem. Each one requires its own app, its own credentials, and its own API integration.

This fragmentation creates a real problem for Airbnb hosts with multiple locks at a property. When Airbnb sets a guest code on your front door lock, it only knows how to talk to the brands it has built direct integrations with. Your garage door lock or side entrance lock — a different brand or even a different model — gets nothing automatically.

Before Seam existed, fixing this meant either paying for a property management system costing hundreds of dollars per month, or manually copying codes into each lock app before every reservation. Neither option is practical for an individual host managing one or two properties.

How Seam Works

Seam works through three core concepts that are worth understanding even if you never write a line of code.

Connect Webviews

A Connect Webview is the authorization screen that Seam shows when you want to link a lock to your Seam account. It looks similar to the "Sign in with Google" experience you have seen on other apps. You choose your lock brand, log in with your existing lock account credentials, and Seam receives permission to control those devices on your behalf.

This is how AirMultiLocks's setup process works. During configuration, you are shown a Seam Connect Webview where you log in to your August, Schlage, or Yale account. After that, AirMultiLocks can read and write access codes on any lock connected to that account.

The Device API

Once locks are connected, Seam exposes them through a clean API. You can list all connected devices, read their current access codes, and issue commands like unlocking a door or adding a new code. Every device, regardless of brand, shows up with the same data structure and the same set of available actions.

Seam also surfaces capability flags for each device — properties that tell you what a specific lock can and cannot do. can_remotely_unlock tells you if a lock can be unlocked via API. can_program_online_access_codes tells you if you can write access codes to it. AirMultiLocks checks these flags before attempting any operation, which prevents errors on locks that do not support certain features.

Access Code Management

Seam has a dedicated access codes API that handles the full lifecycle of PIN codes on smart locks. You can create, update, and delete codes. Codes can be set to activate and deactivate at specific times. And Seam handles the queuing and retry logic when a lock is temporarily offline — so a code set during a sync is guaranteed to reach the device once it reconnects.

Which Smart Locks Does Seam Support?

Seam supports over 100 smart lock brands and models. The brands most commonly used by Airbnb hosts include:

If your lock is already compatible with Airbnb's native integration, it almost certainly has Seam support too. The two platforms overlap significantly in the brands they support.

Why AirMultiLocks Is Built on Seam

AirMultiLocks solves a specific problem: Airbnb only manages access codes on one lock, but most rental properties have more than one guest-accessible door. Guests need the same code to work on the front door, the garage, the side entrance, and the back gate. Maintaining that manually is error-prone and time-consuming.

There were several possible approaches to building this automation. We chose Seam for three reasons.

1. One connection covers every lock brand

Without Seam, AirMultiLocks would need to build and maintain a separate integration for August, a separate one for Schlage, a separate one for Yale, and so on. Each brand changes its API on its own schedule, requires its own authentication, and has its own rate limits. Seam normalizes all of that.

From AirMultiLocks's perspective, reading codes off an August lock and writing them to a Schlage lock is the same operation, using the same API call. Seam handles the translation. This means AirMultiLocks works with any combination of supported locks at your property — you are not locked into a single brand.

2. Access code operations are reliable and queued

Smart locks go offline. Wi-Fi drops. Batteries die. If you try to write an access code directly to a lock's API when the device is unreachable, the operation fails silently and the code never gets set.

Seam queues access code operations and retries them automatically when the device comes back online. For an Airbnb host, this means a code synced by AirMultiLocks before a reservation is virtually guaranteed to reach the lock before the guest arrives — even if there was a brief connectivity issue overnight.

3. Capability flags prevent bad operations

Not every smart lock supports every feature. Some older models can only accept codes with specific length requirements. Some do not support remotely deleting codes. Without capability checks, an app writing codes to unsupported locks would fail unpredictably.

Seam exposes capability flags for every connected device. AirMultiLocks reads these flags before attempting any operation. If a lock does not support a required feature, AirMultiLocks skips it gracefully and logs the reason — rather than failing and potentially leaving your sync in an inconsistent state.

How to Get Started with Seam

Setting up a Seam account is the second step in the AirMultiLocks setup process, and it takes about five to ten minutes. Here is how it works.

1. 1
   Create a free Seam account. Go to console.seam.co and sign up. No credit card is required. You will start in a sandbox workspace, which is a safe testing environment that uses simulated devices.
2. 2
   Connect your smart locks. In the Seam Console, click Add Devices. You will see a Connect Webview. Select your lock brand, enter your existing lock account credentials, and authorize Seam. Repeat this for each lock brand you use across your property.
3. 3
   Create an API key. In the Seam Console, go to Developer → API Keys and create a new key. Copy this key — you will need it during AirMultiLocks setup. Keep it private, as it grants access to control your locks.
4. 4
   Paste the key into AirMultiLocks. During the AirMultiLocks setup wizard, you will be prompted to enter your Seam API key. After validation, AirMultiLocks will list all the locks connected to your Seam account and let you designate which is the primary (Airbnb-connected) lock and which are secondary locks to sync.

Seam + AirMultiLocks: The Complete Multi-Door Solution

Here is what the full system looks like in practice once everything is connected.

Airbnb generates a guest access code for an upcoming reservation and programs it onto your front door lock — the primary lock you have already connected to Airbnb. AirMultiLocks, running on a schedule every 15 minutes, uses the Seam API to read the current code list from that primary lock. It compares what it finds to what it last synced to your secondary locks. If there is a new code, AirMultiLocks tells Seam to write that same code to every secondary lock. When the reservation ends and Airbnb removes the code from the primary lock, AirMultiLocks detects the deletion and removes the corresponding code from every secondary lock.

Your guests experience this as a single, seamless code that works on every door at the property. You experience it as something you set up once and then never think about again.

Frequently Asked Questions

The Takeaway

Seam solves a foundational problem in the smart lock space: the ecosystem is fragmented across dozens of brands, each speaking a different language. By providing a single API that works across all of them, Seam makes it possible to build reliable, multi-brand lock automation without maintaining a dozen separate integrations.

For Airbnb hosts, this matters because it is what makes a product like AirMultiLocks possible. Without Seam, syncing guest codes from your Airbnb front door to every other lock at your property would require enterprise software, a developer on staff, or hours of manual work per reservation. With Seam under the hood, AirMultiLocks can do it automatically, reliably, and across any combination of supported lock brands.

If you have not yet connected your smart lock to Airbnb, start with our guide on how to connect a smart lock to Airbnb. Once that is done, AirMultiLocks and Seam handle the rest.