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Zapier Integration API Reference

The LienDeadline Zapier integration calls these endpoints: OAuth 2.0 authorization, a connection test, two polling triggers, and the Create Deadline Project From Invoice action.

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API base URL

https://secure-api-v1.liendeadline.com

Token, refresh, connection test, triggers and action

Authorization host

https://liendeadline.com

Browser step only: /api/zapier/oauth/authorize

Authentication

OAuth 2.0 authorization code with refresh tokens

JSON over HTTPS

Overview

The integration uses two hosts. The authorization request is a browser step on the website host, https://liendeadline.com, which receives the user’s LienDeadline sign-in session and forwards the request to the API. Every other request goes directly to the API host, https://secure-api-v1.liendeadline.com.

Use HTTPS for every request; the API host redirects plain-HTTP requests to HTTPS. Request and response bodies are JSON, and the token endpoint also accepts form-encoded bodies.

Data routes act on the LienDeadline user who authorized the connection. Every LienDeadline plan includes Zapier access.

Method	Endpoint	Credential	Used for
GET	`/api/zapier/oauth/authorize`liendeadline.com	LienDeadline sign-in session	Start OAuth authorization in the user’s browser
POST	`/api/zapier/oauth/token`secure-api-v1.liendeadline.com	OAuth client ID and secret	Exchange an authorization code or a refresh token
POST	`/api/zapier/oauth/refresh`secure-api-v1.liendeadline.com	OAuth client ID and secret	Refresh tokens; same as the token endpoint with grant_type=refresh_token
GET	`/api/zapier/status`secure-api-v1.liendeadline.com	Bearer access token	Connection test and connection label
GET	`/api/zapier/v2/triggers/upcoming`secure-api-v1.liendeadline.com	Bearer access token	Upcoming Deadline trigger
GET	`/api/zapier/v2/triggers/reminders`secure-api-v1.liendeadline.com	Bearer access token	Deadline Reminder trigger
POST	`/api/zapier/webhook/invoice`secure-api-v1.liendeadline.com	Bearer access token	Create Deadline Project From Invoice action

Authentication: OAuth 2.0

The integration uses the OAuth 2.0 authorization code grant with refresh tokens. The client secret is used only in server-to-server token requests. LienDeadline stores hashes of authorization codes, access tokens and refresh tokens, not the tokens themselves.

1. Authorization request

GEThttps://liendeadline.com/api/zapier/oauth/authorize

Zapier opens this URL in the user’s browser with these query parameters. Use the website host, not the API host: the LienDeadline sign-in session cookie is only sent to liendeadline.com, and the website forwards the request to the API with it.

Parameter	Required	Description
`response_type`	Yes	Must be `code`.
`client_id`	Yes	The integration’s OAuth client ID.
`redirect_uri`	Yes	Where LienDeadline sends the result. It must be a Zapier OAuth callback URL (`https://zapier.com/dashboard/auth/oauth/return/…`, also accepted on `www.zapier.com`, or `https://hooks.zapier.com/hooks/oauth/…`) or a URI that LienDeadline has allowlisted.
`state`	No	Returned unchanged on the redirect to redirect_uri, including error redirects.
`scope`	No	Stored with the grant and returned in the token response. The Zapier app sends `zapier:read zapier:write`.

If the user is signed in, LienDeadline issues an authorization code for that user and redirects to redirect_uri with code and state. There is no consent screen. The code can be used once and expires after 10 minutes by default.

If the user is not signed in, LienDeadline redirects to its sign-in page, https://liendeadline.com/auth/login, with the authorization URL in the next parameter. After sign-in, the browser returns to the authorization URL and LienDeadline redirects straight back to Zapier with the code.

Successful redirect

HTTP/1.1 307 Temporary Redirect
Location: REDIRECT_URI?code=AUTHORIZATION_CODE&state=STATE_FROM_REQUEST

A missing or unaccepted redirect_uri returns 400 with invalid_request as JSON, without a redirect. Other failures redirect to redirect_uri with error, error_description and state:

unsupported_response_type: response_type is not code.
unauthorized_client: the client_id is not recognized.
access_denied: the signed-in account has no matching LienDeadline profile, or its plan does not include Zapier access.

2. Token request

POSThttps://secure-api-v1.liendeadline.com/api/zapier/oauth/token

Exchange the authorization code for tokens, and later refresh them. This is a server-to-server request to the API host. Send parameters as application/x-www-form-urlencoded, as the Zapier app does, or as a JSON object with Content-Type: application/json. Authenticate the client with client_id and client_secret in the body or with HTTP Basic authentication; body values take precedence.

Parameter	Grant type	Description
`grant_type`	Both	`authorization_code` or `refresh_token`.
`code`	authorization_code	The code from the authorization redirect.
`redirect_uri`	authorization_code	Must match the redirect_uri sent in the authorization request.
`refresh_token`	refresh_token	The most recent refresh token issued to the connection.
`client_id`	Both	Required unless sent with HTTP Basic authentication.
`client_secret`	Both	Required unless sent with HTTP Basic authentication.

Exchange an authorization code

curl -X POST "https://secure-api-v1.liendeadline.com/api/zapier/oauth/token" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Accept: application/json" \
  --data-urlencode "grant_type=authorization_code" \
  --data-urlencode "code=AUTHORIZATION_CODE" \
  --data-urlencode "redirect_uri=REDIRECT_URI" \
  --data-urlencode "client_id=YOUR_CLIENT_ID" \
  --data-urlencode "client_secret=YOUR_CLIENT_SECRET"

Refresh tokens

curl -X POST "https://secure-api-v1.liendeadline.com/api/zapier/oauth/token" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Accept: application/json" \
  --data-urlencode "grant_type=refresh_token" \
  --data-urlencode "refresh_token=REFRESH_TOKEN" \
  --data-urlencode "client_id=YOUR_CLIENT_ID" \
  --data-urlencode "client_secret=YOUR_CLIENT_SECRET"

200 response (both grant types)

{
  "access_token": "ACCESS_TOKEN",
  "token_type": "Bearer",
  "refresh_token": "REFRESH_TOKEN",
  "expires_in": 3600,
  "scope": "zapier:read zapier:write",
  "email": "ops@example.com"
}

Field	Type	Description
`access_token`	string	Opaque bearer token for the data routes.
`token_type`	string	Always `Bearer`.
`refresh_token`	string	Opaque token for the next refresh. Every successful token request returns a new one.
`expires_in`	integer	Access-token lifetime in seconds; 3600 by default.
`scope`	string	The scope recorded at authorization, or an empty string.
`email`	string	Email address of the LienDeadline account that authorized the connection.

Refresh alias

POSThttps://secure-api-v1.liendeadline.com/api/zapier/oauth/refresh

Accepts the same parameters and returns the same responses as the token endpoint, with grant_type set to refresh_token. The Zapier app refreshes through /api/zapier/oauth/token.

Token lifecycle

Access tokens expire after expires_in seconds. When a data route returns 401, the Zapier integration refreshes the access token automatically.
Refresh tokens are valid for 180 days by default and rotate: each successful refresh revokes the refresh token it used and returns a new one. A reused, revoked or expired refresh token returns invalid_grant.
Each LienDeadline user has one active Zapier access token. Issuing a new access token, by code exchange or by refresh, revokes the previous one.
Completing a new authorization also revokes the user’s earlier refresh tokens, so an older Zapier connection to the same LienDeadline user stops working until it is reconnected.

OAuth errors

The token and refresh endpoints return errors as JSON with error and error_description.

Status	error	When
400	`invalid_request`	A required parameter is missing: code or redirect_uri for authorization_code, or refresh_token for refresh_token. The authorization endpoint also returns it for a missing or unaccepted redirect_uri.
400	`invalid_grant`	The authorization code is invalid, expired, already used or was issued for another redirect_uri, or the refresh token is invalid, expired or already used.
400	`unsupported_grant_type`	grant_type is not authorization_code or refresh_token.
401	`invalid_client`	The client ID or client secret is missing or wrong. Client authentication is checked before the grant.
500	`server_error`	OAuth is not configured on the server.

Error response

{
  "error": "invalid_grant",
  "error_description": "Invalid, expired, or already used authorization code."
}

Calling the data routes

Send the access token in the Authorization header. A missing, unknown, expired or revoked token returns 401 with {"detail": "Unauthorized"}.

Authorization: Bearer ACCESS_TOKEN

Connection test

Connection status

GEThttps://secure-api-v1.liendeadline.com/api/zapier/status

Zapier calls this route to test the connection and uses email as the connection label.

Request

curl "https://secure-api-v1.liendeadline.com/api/zapier/status" \
  -H "Authorization: Bearer ACCESS_TOKEN"

200 response

{
  "connected": true,
  "token_last4": "a1b2",
  "token_created_at": "2026-10-01T15:30:00+00:00",
  "auth_mode": "oauth2",
  "oauth_ready": true,
  "email": "ops@example.com"
}

Field	Type	Description
`connected`	boolean	`true` when the user has an active access token.
`token_last4`	string	Last four characters of the active access token.
`token_created_at`	string	ISO 8601 time the active access token was issued.
`auth_mode`	string	Always `oauth2`.
`oauth_ready`	boolean	Always `true`.
`email`	string	Email address of the LienDeadline account that authorized the connection.

Triggers

Both triggers are polling endpoints that return a top-level JSON array. They cover projects that belong to the connected LienDeadline user. Invoices imported from QuickBooks are included only after their project type is confirmed. Dates are calculated in UTC.

Query parameters

Parameter	Type	Default	Description
`limit`	integer, 1–500	50	Maximum number of items returned.
`days_ahead`	integer, 1–365	30 (upcoming), 14 (reminders)	Window in days from today. Deadlines from today through today plus days_ahead are included.
`since`	ISO 8601 date-time	None	Only include projects updated at or after this time.

A value outside these ranges, or a since value that is not a date-time, returns 422.

Upcoming Deadline

GEThttps://secure-api-v1.liendeadline.com/api/zapier/v2/triggers/upcoming

Returns one item per project whose lien filing deadline falls inside the window, most recently updated projects first. deadline_date is the lien filing deadline.

Request

curl -G "https://secure-api-v1.liendeadline.com/api/zapier/v2/triggers/upcoming" \
  -H "Authorization: Bearer ACCESS_TOKEN" \
  --data-urlencode "limit=50" \
  --data-urlencode "days_ahead=30"

Deadline Reminder

GEThttps://secure-api-v1.liendeadline.com/api/zapier/v2/triggers/reminders

Returns an item when a project’s preliminary notice or lien filing deadline is exactly one of the project’s reminder days away (1, 7 or 30 days), most recently updated projects first. deadline_date is the deadline that matched.

Only projects with Zapier reminders turned on in LienDeadline are included. Projects created by the action start with Zapier reminders turned off. A reminder day larger than days_ahead never matches, so set days_ahead to 30 or more to receive 30-day reminders.

Trigger item fields

Field	Type	Description
`id`	string	Deduplication key: a 32-character hash of the trigger type, deadline type, project, deadline date, days remaining and the project’s last update time.
`trigger_type`	string	`upcoming_deadline` or `deadline_reminder`.
`account_id`	string or null	LienDeadline account that owns the project.
`project_id`	string	LienDeadline project ID.
`project_name`	string	Project name, or an empty string.
`customer_name`	string	Client name saved on the project, or an empty string.
`state`	string	Project state, normally a two-letter code such as `TX`.
`deadline_date`	string	Deadline date, `YYYY-MM-DD`.
`days_until_deadline`	integer	Days from today (UTC) to deadline_date.
`source_updated_at`	string	ISO 8601 time the project was last updated, or its creation time when no update is recorded.
`updated_at`	string	Same value as `source_updated_at`.
`deep_link_url`	string	Link to the project in the LienDeadline dashboard. Opening it requires signing in.

Zapier skips items whose id it has already seen. Because the id includes the days remaining, an upcoming deadline gets a new id on each day it stays in the window, and editing a project also produces a new id. A reminder item appears only on the day its reminder is due.

200 response

[
  {
    "id": "0f1e2d3c4b5a69788796a5b4c3d2e1f0",
    "trigger_type": "upcoming_deadline",
    "account_id": "00000000-0000-4000-8000-000000000001",
    "project_id": "00000000-0000-4000-8000-000000000002",
    "project_name": "Example Warehouse Retrofit",
    "customer_name": "Example Supply Co.",
    "state": "TX",
    "deadline_date": "2027-01-15",
    "days_until_deadline": 103,
    "source_updated_at": "2026-10-01T15:30:00+00:00",
    "updated_at": "2026-10-01T15:30:00+00:00",
    "deep_link_url": "https://liendeadline.com/dashboard?project=00000000-0000-4000-8000-000000000002"
  }
]

Action: Create Deadline Project From Invoice

Create a deadline project

POSThttps://secure-api-v1.liendeadline.com/api/zapier/webhook/invoice

Calculates the preliminary notice and lien filing deadlines for an invoice and saves the result as a project in the connected LienDeadline account.

Header	Required	Description
`Authorization`	Yes	`Bearer ACCESS_TOKEN`
`Content-Type`	Yes	`application/json`
`X-Zapier-Event-Id`	No	Idempotency key. See Retries and duplicates below.

Body field	Type	Required	Description
`state`	string	Yes	Two-letter code or full name of one of the 50 states or DC, in any letter case.
`invoice_date`	string	Yes	`YYYY-MM-DD` or `MM/DD/YYYY`. Saved and returned as `YYYY-MM-DD`.
`invoice_amount_cents`	integer	One amount	Invoice amount in cents, 0 or more. The Zapier action sends this field.
`invoice_amount`	number	One amount	Invoice amount in dollars, 0 or more. Used only when invoice_amount_cents is absent.
`project_name`	string	No	Project name.
`client_name`	string	No	Client name. Triggers return it as `customer_name`.
`project_type`	string	No	`Commercial` (default) or `Residential`.
`role`	string	No	Your role on the project, such as `supplier` (default) or `contractor`.
`notes`	string	No	Notes saved on the project.
`invoice_number`	string	No	Sent by the Zapier action. The API does not currently save or return it.

The API ignores body fields not listed here. A missing state or invoice_date, a date in another format, or an invoice_amount_cents value that is negative or not a whole number returns 422. An unrecognized state name, a state code LienDeadline does not support (the error has code UNSUPPORTED_STATE), a negative invoice_amount, or a request without either amount field returns 400.

Request

curl -X POST "https://secure-api-v1.liendeadline.com/api/zapier/webhook/invoice" \
  -H "Authorization: Bearer ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -H "X-Zapier-Event-Id: zapier-source-INV-1001" \
  -d '{
    "state": "TX",
    "invoice_date": "2026-09-15",
    "invoice_amount_cents": 499200,
    "project_name": "Example Warehouse Retrofit",
    "client_name": "Example Supply Co.",
    "project_type": "Commercial",
    "role": "supplier"
  }'

201 response

{
  "success": true,
  "version": "v1",
  "id": "00000000-0000-4000-8000-000000000002",
  "project_name": "Example Warehouse Retrofit",
  "invoice_date": "2026-09-15",
  "state": "TX",
  "invoice_amount": "4992.00",
  "invoice_amount_cents": 499200,
  "preliminary_deadline": "2026-11-15",
  "preliminary_deadline_days": 42,
  "lien_deadline": "2027-01-15",
  "lien_deadline_days": 103,
  "message": "Project created successfully"
}

Example values are synthetic. Dates show the format only and are not deadline guidance.

Field	Type	Description
`success`	boolean	`true` when the project was created.
`version`	string	Always `v1`.
`id`	string	ID of the new LienDeadline project.
`project_name`	string	Project name, or an empty string.
`invoice_date`	string	Invoice date, `YYYY-MM-DD`.
`state`	string	Two-letter state code.
`invoice_amount`	string	Amount in dollars with two decimal places.
`invoice_amount_cents`	integer	Amount in cents.
`preliminary_deadline`	string or null	Preliminary notice deadline, `YYYY-MM-DD`, or `null` when none was calculated.
`preliminary_deadline_days`	integer or null	Days from today to the preliminary notice deadline.
`lien_deadline`	string	Lien filing deadline, `YYYY-MM-DD`.
`lien_deadline_days`	integer	Days from today to the lien filing deadline.
`message`	string	`Project created successfully`

Retries and duplicates

Send X-Zapier-Event-Id to make retries safe. LienDeadline records each value per user in the same transaction that saves the project. A later request from the same user with the same value creates nothing and returns 200 without the project ID or deadlines. If a request fails before the project is saved, for example at the plan limit, the value is not recorded and a retry can succeed.

The Zapier action sets this header from its Deduplication key input (dedupe_key) as zapier-source- followed by the key. Without a key, it uses an identifier from the Zapier run when one is available, or otherwise a hash of the request body. Map a value that identifies the source invoice, such as its record number in your accounting app.

200 response for a repeated X-Zapier-Event-Id

{
  "success": true,
  "version": "v1",
  "duplicate": true,
  "message": "Event already processed"
}

Plan limits

Each project the action creates counts as one protected item toward the account’s plan limit (see Pricing). When the limit is reached, the action creates nothing and returns 402. Repeated requests that return the duplicate response do not count.

402 response

{
  "success": false,
  "version": "v1",
  "code": "LIMIT_REACHED",
  "limit_type": "manual_calcs",
  "used": 3,
  "limit": 3,
  "plan": "free"
}

Errors & limits

These statuses apply to the connection test, trigger and action routes.

Status	Meaning	Response body
400	Action only: unrecognized state name, unsupported state code (code UNSUPPORTED_STATE), negative invoice_amount, or no amount field.	`{"success": false, "version": "v1", "error": "…"}`
401	Missing, unknown, expired or revoked access token. The Zapier integration refreshes the token automatically.	`{"detail": "Unauthorized"}`
402	Action only: the plan’s protected-item limit is reached.	`code` is `LIMIT_REACHED`; see Plan limits.
403	Triggers and action: the account’s plan does not include Zapier access.	`code` is `PLAN_NOT_ALLOWED`, inside `detail` for the triggers.
422	Invalid query parameter or request body.	`{"detail": [{"loc": […], "msg": "…", "type": "…"}]}`
429	Rate limit exceeded; see Rate limits below. The response has no Retry-After header. Zapier treats 429 as throttling and retries later.	`{"error": "Rate limit exceeded: 10 per 1 minute"}`
500	The deadline could not be calculated for a supported state, or the project could not be saved.	`{"detail": "…"}` or `{"success": false, "version": "v1", "error": "…"}`

Rate limits

Route	Limit
`GET /api/zapier/v2/triggers/upcoming`	60 requests per minute
`GET /api/zapier/v2/triggers/reminders`	60 requests per minute
`POST /api/zapier/webhook/invoice`	10 requests per minute

Support

For integration questions or access problems, email support with the request path, the response status and body, and the approximate time of the request. Never send access tokens, refresh tokens or client secrets.

Email support Zapier setup guide Customer API docs