Buildium API: Webhooks, Limits, and Carly Workflows
A tenant calls about a leak while the property manager is standing in another unit. A text to Carly can create the Buildium work order before the details are lost. Carly can also answer a lease question before a tenant call, send a morning maintenance brief, start renewal outreach on a schedule, and turn a configured Buildium event into the right vendor, applicant, or unit-turn workflow.
Buildium’s Premium-plan API provides the underlying read/write access and a broad webhook catalog. Carly turns that access into on-demand, recurring, and event-triggered work across Buildium, email, Slack, calendars, tasks, and the rest of the property team’s stack.
Three ways Carly works with Buildium
1. Handle Buildium work by email or text
Carly connects directly to Buildium with your API credentials. When a tenant calls about a leak, text Carly the unit, issue, priority, and access notes and have it create the work order while the details are fresh. Ask whether a tenant is current before a collection call, pull the lease end date for a unit, or update a property record from the field. These capabilities match the direct Buildium integration; they do not require a webhook.
2. Run recurring portfolio checks
A Carly workflow can run on the cadence you set. Send a morning digest of open high-priority work orders, a weekly list of leases approaching renewal, or a daily rent-status summary before collection calls begin. The workflow queries Buildium, formats the result, and can deliver it through email or Slack without anyone opening a chat.
Scheduled checks use API calls, so they should be scoped and paginated deliberately. They are useful even when no corresponding Buildium event exists, but they are not the same as real-time monitoring.
3. Start a workflow from a Buildium event
Buildium can send a supported event to a public HTTPS callback URL. Point that subscription at a Carly workflow webhook endpoint, validate the Buildium signature, and configure what the workflow should do next. For example:
WorkOrder.Created→ fetch the full work order, notify the assigned manager, and prepare the vendor email for the routing rules you approved.Applicant.Created→ retrieve the applicant record, send an acknowledgement, and create a review task. Screening still depends on the screening service and policies you connect.Lease.MoveOut.Created→ create the turn checklist, place the inspection on the calendar, and notify the portfolio owner.
The event does not perform those actions by itself. Buildium sends a thin payload, the workflow makes a follow-up API request for the record, and each email, calendar update, task, or Buildium write must be configured with the right permissions and safeguards.
The webhook catalog
Buildium documents events across leases, lease transactions and move-outs, work orders, tasks and task history, applicants, rentals and units, associations and ownership accounts, bills and payments, vendors, budgets, listings, phone logs, meter readings, and bank accounts. Many are .Created / .Updated / .Deleted triples, while others are narrower.
Payloads are deliberately thin — an event name, a timestamp, and IDs:
{ "EventName": "Rental.Updated", "EventDateTime": "2022-05-10T15:12:46Z", "AccountId": 123456, "PropertyId": 23 }Every event is a trigger plus a follow-up GET for the actual record. A Carly workflow can make that second call when you configure it; if you’re building the receiver yourself, budget for it.
Carly adds the assistant and workflow layer
Carly’s Buildium connection and workflow engine cover different parts of the job:
- Direct assistance: create work orders, check rent status, look up leases and tenants, and update records by email or text.
- Recurring workflows: run portfolio checks and deliver digests on a daily, weekly, or custom schedule.
- Event-started workflows: use a Buildium webhook subscription to start a configured Carly workflow in near real time.
- Cross-app action: send email through Gmail or Outlook, post to Slack, add calendar events, create tasks, and write approved results back to Buildium.
- Free workflow plumbing: non-AI Zapier-style steps run free; AI agents start at $35/month.
This is where Carly differs from a Claude or ChatGPT conversation.
ChatGPT Scheduled Tasks and Claude Cowork both run unattended on timers. Their ordinary task schedulers do not subscribe directly to arbitrary events in connected business apps. ChatGPT Workspace Agents can be invoked through an API, but an upstream system must still detect the event and call it.
A chat model can analyze an export when prompted; a Carly workflow can run on the event or schedule you configured without leaving a chat open.Connect Buildium with the client ID and secret from a scoped API key on the Carly integrations page. If the workflow starts from a Buildium event, create and test the webhook subscription separately in Buildium. If you’re comparing more broadly, see the best AI tools for property managers.
Turning the Buildium API on
If you’re on Premium you already have the Open API and it’s off by default. Two admin steps, and skipping the first makes the second invisible:
- Enable it — Settings > Application settings > System preferences > Api settings, toggle Open API on, save.
- Create a key — Settings > Developer Tools > Create API Key, then check the boxes for the entities it should reach. Keys are scopable and can be read-only, worth doing rather than minting full access out of habit.
The secret displays once. Lose it and you delete the key and start over.
Webhook subscriptions are created at Settings > Developer Tools > Webhooks, UI-only — there’s no endpoint for managing them programmatically.
There’s a free sandbox at apisandbox.buildium.com, live in two or three minutes with realistic sample data. One per account, capped at 1,500 units, no outbound email. Before you lean on it: you cannot reset it and you cannot delete it.
Reference: Buildium API limits and sharp edges
Auth is a client ID and secret on every request, as x-buildium-client-id and x-buildium-client-secret. No OAuth, no CORS; Buildium recommends server-to-server only.
Rate limit is 10 concurrent requests per second, then a 429 with a suggested 200ms retry.
Three failures that don’t look like what they are:
- Query strings cap at 4,096 characters; going over returns a 500, so a long filter list looks like a Buildium outage.
limitandoffsetare case-sensitive, and the wrong case returns 404. So does the wrong case in a URL path.- Pagination defaults to 50 and caps at 1,000. Check
X-Total-Countor you’ll silently process a fraction.
Webhook delivery allows 10 seconds to respond, retries at 1 minute, 10 minutes, and 1 hour, then drops the event permanently. Twenty consecutive failures suspends the subscription. Signature is HMAC-SHA256 over timestamp . body. Duplicates happen and ordering isn’t guaranteed (Lease.Created may arrive after Tenant.Created), so make processing idempotent.
ngrok is blocked for webhook callbacks, which breaks the usual local development loop.
Appliance endpoints retire on October 19, 2026. Everything under /v1/rentals/appliances* and /v1/associations/appliances* starts returning 410 Gone and moves to /v1/inventoryassets. If you have an existing integration, that’s the one to action now.
Frequently Asked Questions
What can you automate with the Buildium API?
The API can support workflows around work orders, applicants, move-outs, leases, accounting records, vendors, tasks, properties, and units. A webhook only announces the event and its record identifiers; your workflow must fetch the full record and define every follow-up action. Carly can provide that workflow layer as well as on-demand and scheduled access to Buildium.
How do I get Buildium API keys?
Two steps, both requiring an administrator role. Enable the API at Settings > Application settings > System preferences > Api settings, then create a key at Settings > Developer Tools > Create API Key and choose which entities it can reach. The secret displays once and cannot be recovered.
Does the Buildium API support webhooks?
Yes. Buildium documents a broad event catalog delivered in near real time and signed with HMAC-SHA256. Payloads contain identifiers rather than the full record, so each event usually needs a follow-up API call. Your endpoint has 10 seconds to respond, gets three retries, and the subscription suspends after 20 consecutive failures.
How does Carly connect to Buildium?
Carly connects with a scoped Buildium API key: the client ID and secret authenticate the reads and writes you authorize. For event-driven work, you also create a Buildium webhook subscription that points to the workflow’s HTTPS endpoint. For recurring work, set the schedule in Carly instead.
Can Carly run a workflow from a Buildium event?
Yes, after setup. Configure Buildium to send the chosen event to the Carly workflow webhook endpoint, validate the signature, and define the downstream steps. The flow can fetch the Buildium record, send email through Gmail or Outlook, update a calendar or task system, and write an approved result back. Connecting the API key alone does not subscribe Carly to Buildium events.
When do the Buildium appliance endpoints stop working?
October 19, 2026, when all deprecated /v1/rentals/appliances* and /v1/associations/appliances* routes begin returning 410 Gone. They’re replaced by the Inventory & Assets API at /v1/inventoryassets.
More: Best AI tools for property managers · Best AI tools for landlords · Claude + Buildium · Best AI workflow automation tools
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