Developers • v1 Reference

LienDeadline API Documentation

A production-style API reference for deadline automation. Use one endpoint to retrieve mechanics lien calculations across all 50 states and DC with enterprise-grade consistency.

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Base URL

https://api.liendeadline.com/v1

Target SLA

99.9% uptime for Automated plan

Coverage

All 50 states + DC

Overview

Use the API to calculate and monitor upcoming preliminary notice and lien filing deadlines from invoice data. The public docs below focus on authenticated production usage; request bodies are intentionally strict, and validation errors are returned in a machine-readable format.

Use Cases

Bulk invoice deadline calculations
Automated reminders into Slack/Email/Sales workflows
In-app validation before invoice closeout

Response Contract

JSON bodies with UTC timestamps
State-specific deadline logic applied server side
Consistent error shape with request correlation IDs

Quickstart

Start by requesting API access and testing your first calculation request.

POST /api quickstart

curl -X POST "https://api.liendeadline.com/v1/calculate-deadline" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "invoice_date": "2025-01-15",
    "state": "CA",
    "role": "supplier",
    "project_type": "commercial"
}'

The response contains both preliminary notice and lien filing deadlines and remaining-day counters.

API playground

Use the interactive playground to send test requests, validate payloads, and inspect responses before integrating.

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What you get

Clear endpoint docs and schemas
Sample payloads with real response shapes
Live try-it execution from browser

What it proves

Production-fit for high-volume invoicing
State-specific logic from one contract
Clear onboarding story for internal teams

Decision support

Scoped to demo-safe public endpoints
Safe for prospect walkthroughs
Consistent language your support team can quote

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Authentication

Include your API key in the request header as a Bearer token.

Authorization: Bearer YOUR_API_KEY

Authorization best practices

Store keys in secret management services only
Rotate long-lived keys if team members change
Do not pass credentials in query strings

Common headers

Content-Type: application/json
Accept: application/json
Idempotency-Key (optional)

Endpoints

POST

/api/v1/calculate-deadline

Calculate preliminary notice and lien filing deadlines from invoice/project details.

Field	Type	Required	Description
invoice_date	string	Yes	Date in YYYY-MM-DD format
state	string	Yes	US state code (2 letters)
role	string	Yes	supplier, contractor, or subcontractor

{
  "preliminary_notice": {
    "required": true,
    "deadline": "2025-02-04",
    "days_from_now": 20
  },
  "lien_filing": {
    "deadline": "2025-04-15",
    "days_from_now": 90
  },
  "warnings": [
    "If Notice of Completion is filed, deadline can shorten to 30 days"
  ],
  "statute_citations": [
    "Cal. Civ. Code §8204(a)",
    "Cal. Civ. Code §8414"
  ]
}

GET

/api/v1/supported-states

Return the list of supported jurisdictions used for validation and routing.

{
  "states": ["AL", "AK", "AZ", "AR", "...", "WY", "DC"],
  "count": 51
}

GET

/api/v1/state-guides/{state}

Pull state-specific guidance and rules when you need context for internal auditability.

{
  "state": "CA",
  "state_name": "California",
  "notice_window_days": 90,
  "filing_deadline_rule": "30-day rule when notice of completion is filed",
  "references": ["Cal. Civ. Code §8200-8444"]
}

GET

/api/v1/state-guides/index

Lightweight list endpoint used for dropdowns and UI controls before opening full guides.

{
  "states": [
    { "state_code": "CA", "title": "California Mechanics Lien" },
    { "state_code": "TX", "title": "Texas Preliminary Notice" }
  ]
}

GET

/api/v1/state-guides/{state}/calculator-payload

Fetches normalized rule payload exactly as used by the calculator for downstream integrations.

{
  "state_code": "CA",
  "state_name": "California",
  "rule_payload": {
    "preliminary_notice": {
      "required": true,
      "days": 20,
      "when": "Notice of completion may shorten timing"
    },
    "lien_filing": {
      "required": true,
      "days": 90
    }
  }
}

Code examples

Choose your stack and keep requests minimal.

Example

curl

Raw HTTP call you can run in terminal or scripts.

Language

curl -X POST "https://api.liendeadline.com/v1/calculate-deadline" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "invoice_date": "2025-01-15",
    "state": "CA",
    "role": "supplier",
    "project_type": "commercial"
}'

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Errors & limits

HTTP status	Meaning	Action
200	Success	Use response payload as delivered
400	Invalid request data	Check required fields and type formats
401	Authorization failure	Regenerate API key and retry
403	Plan restrictions	Upgrade plan for API feature access
429	Rate limit reached	Back off and retry with jitter

Rate policy

Requests are throttled by plan and account. Burst and sustained limits are enforced on authenticated credentials to protect shared infrastructure.

Support & next steps

For technical access requests, plan-specific feature questions, and integration troubleshooting, use our support channels.

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Need a custom SLA? Enterprise customers can request a dedicated integration playbook and SLA addendum.