August Wi-Fi Smart Lock Review (2026): Retrofit Install, Built-In Wi-Fi, No Bridge

Most smart locks ask for a small act of demolition: the old deadbolt comes out, a new one goes in, and the door is never quite what the landlord handed over. The August Wi-Fi Smart Lock, now in its fourth generation, takes the opposite approach. It mounts on the inside of the deadbolt already there, turns the existing thumb-turn by motor, and leaves the exterior cylinder, the keys, and the door itself untouched. What it adds is the smart layer: built-in Wi-Fi with no bridge, remote locking from anywhere, auto-lock and auto-unlock, and a DoorSense sensor that reports whether the door is actually closed. For renters, and for anyone happy with the deadbolt they already own, that combination is the entire pitch.

This review reads the lock against August's published specifications and the way a retrofit lives on a door, with the no-subscription reality stated plainly and the trade at the heart of the design named just as plainly: the lock is only ever as strong as the deadbolt it rides on.

The retrofit that keeps your deadbolt

Installation is the reason this lock exists. August rates the job at under ten minutes: the interior thumb-turn escutcheon comes off, the mounting plate and adapter go on over the existing tailpiece, and the lock body seats on top. Nothing on the outside of the door changes, so every key that opened the door yesterday opens it today, and the whole installation reverses cleanly at the end of a lease. The lock is compatible with most single-cylinder deadbolts, the standard arrangement with a keyed cylinder outside and a thumb-turn inside, and August publishes a compatibility checker worth consulting before buying.

The compact body helps the retrofit case: at 72 millimetres across and 46 deep, the interior unit is a small round puck, and from the street nothing signals a smart lock is fitted.

Built-in Wi-Fi, no bridge

Older August locks reached the internet through a separate Connect bridge. The fourth-generation Wi-Fi Smart Lock builds the radio in: it joins the home network directly over 802.11 b/g/n Wi-Fi on the 2.4 or 5 GHz band, with Bluetooth alongside for setup and close-range control. There is no hub to buy and no pairing step beyond the free August app on iOS or Android.

Because the lock is genuinely online, locking and unlocking work from anywhere, smart alerts fire when the door's status changes, and voice control works through Alexa, Google Assistant, and Siri. A phone, or an Apple Watch, becomes a key that works from the office as readily as from the doorstep. The SwitchBot Lock Pro, the other retrofit reviewed here, speaks Bluetooth alone unless a separately sold hub joins it; on the August, remote access is simply included.

Auto-Lock, Auto-Unlock, and DoorSense

The automation layer is where the August earns daily loyalty. Auto-Unlock uses geo-fencing: the app notices the phone arriving home and opens the deadbolt as the door is reached. Auto-Lock runs the other way, throwing the bolt once the door is closed or after a chosen delay of up to thirty minutes, so the door stops depending on anyone remembering it.

What separates August's automation from a plain timer is DoorSense. A small sensor included in the box reports whether the door is open or securely closed, so the app can answer the question that actually matters at distance, not "did I lock it" but "is it shut and locked." Auto-lock logic can key off that closed state rather than firing blind, and smart alerts can flag a door left ajar, not merely one left unlocked.

Guest keys, the app, and the subscription question

Access sharing runs through virtual guest keys in the August app: a key can be sent to a family member, a sitter, or a guest and revoked just as easily, and an activity feed logs who came and went and when. Buyers who want codes at the door can add August's keypad bundles, including a Keypad Touch with fingerprint access, but neither is part of this lock; app, voice, auto-unlock, and the original physical key are the built-in ways in.

On recurring cost, the August sits comfortably with this site's premise. The app is free, and the core features reviewed here, remote access, auto-lock and unlock, DoorSense, guest keys, alerts, and the activity feed, carry no monthly fee. On security plumbing, August documents Bluetooth Low Energy encryption and TLS in its mobile apps, mandatory two-factor authentication on the account, and a lost-phone page at lostphone.august.com that disables the app and every virtual key from any device. An optional biometric verified access setting can require the phone's fingerprint or face check before the app opens the door.

What the retrofit design gives up

Honesty requires naming what this lock is not. It is not a keypad lock: there is no number pad on the door, and anyone who wants code entry without a phone needs the separate keypad accessory. It is not a fingerprint lock either, unless the Keypad Touch bundle joins it. And it is not a security upgrade to the door's hardware. The deadbolt that resists kicking and prying tomorrow is the same deadbolt fitted yesterday, because the August only motors the thumb-turn; a buyer whose real need is a Grade-rated replacement should look at a full deadbolt like the Schlage Encode instead. Finally, the lock runs on two CR123 batteries, included in the box, rather than the standard AA cells most locks take.

Who should buy it

The August Wi-Fi Smart Lock is the right lock for a renter who cannot touch the deadbolt but refuses to give up remote control, and for any homeowner content with their existing hardware who wants the smart layer without the swap, with no bridge, no hub, and no monthly fee.

Who should skip it

Buyers who want to tap a code into the door should skip this listing; no keypad is built in and the accessory is a separate purchase. Doors without a compatible single-cylinder deadbolt need a different lock entirely. And anyone replacing a worn or unrated deadbolt should spend the budget on a certified full replacement rather than a motor for hardware that was never the strong point.

How it compares

Against the SwitchBot Lock Pro, the August wins on built-in Wi-Fi, which the SwitchBot reaches only through a separately sold hub. Against the Schlage Encode, the split is replacement versus retrofit: the Encode is a complete Wi-Fi deadbolt with a built-in keypad and a security grade, while the August keeps the existing deadbolt and keys. Against the Wyze Lock Bolt, the budget pick, the August costs more but delivers the remote layer the Bluetooth-only Wyze deliberately omits. And against the Yale Assure Lock 2, the choice is again a full replacement with keypad options versus a renter-safe retrofit. The August is the pick when keeping the door's existing hardware is the requirement, not a compromise.

Verdict

The August Wi-Fi Smart Lock does the retrofit brief about as completely as it can be done. It installs over the existing deadbolt in minutes, keeps every original key working, and then delivers the features that usually demand replacement hardware: built-in Wi-Fi with no bridge, remote control and alerts, geo-fenced auto-unlock, timer or closed-door auto-lock, and a DoorSense sensor that confirms the door is shut, all in the free app with no subscription. The costs of the design are real, no built-in keypad or fingerprint reader, CR123 batteries rather than AAs, and a security ceiling set by whatever deadbolt it rides on, but they are the honest price of a lock that leaves the door exactly as it found it. For renters especially, that is not a compromise. It is the point.

Frequently asked questions

Can the August Wi-Fi Smart Lock be unlocked remotely?

Yes. Wi-Fi is built into the lock itself, with no bridge or hub required, so the August app can lock, unlock, and check the door from anywhere. Smart alerts report changes in the door's status, and voice control works through Alexa, Google Assistant, and Siri.

Is there a monthly fee?

No. The August app is free, and the core features, remote access, auto-lock and auto-unlock, DoorSense, virtual guest keys, smart alerts, and the activity feed, carry no recurring charge.

Will it work with an existing deadbolt and existing keys?

The lock fits most single-cylinder deadbolts, the common arrangement with a keyed cylinder outside and a thumb-turn inside, and August publishes a compatibility checker to confirm before buying. Because installation only covers the interior thumb-turn, the exterior cylinder is untouched and every existing key keeps working.

How do guests get in, and what powers the lock?

Virtual guest keys can be sent and revoked in the app, and buyers who want code entry at the door can add August's separately sold keypad, including a Keypad Touch option with fingerprint access. The lock itself runs on two CR123 batteries, which come included in the box.