IACS Vessel Classification Data API: How to Query Class Status by IMO Number

If you're building maritime software, you've probably needed vessel classification data at some point — the class society, survey dates, class status, reason for withdrawal. The kind of data you need to assess compliance, flag risk, or populate a fleet dashboard.

That data exists. IACS (the International Association of Classification Societies) publishes it. But getting it into your application programmatically is a different story.

What is IACS vessel classification data?

IACS member societies — DNV, Lloyd's Register, Bureau Veritas, ClassNK, ABS, and others — collectively classify over 90% of the world's cargo-carrying tonnage. When a vessel is "in class," it means the hull and machinery meet the society's rules and have been surveyed on schedule.

The data IACS publishes includes:

This data matters for insurers underwriting marine risk, port state control systems checking compliance, ship operators tracking their fleet, and any maritime SaaS product that displays vessel information.

The problem: getting this data into your application

IACS publishes vessel-in-class data on their website as a downloadable ZIP file containing a semicolon-delimited CSV. There is no API. No webhook. No structured feed.

To use this data programmatically, you typically have to:

1. Scrape the IACS website to find the latest download link
2. Download and extract the ZIP file (~50MB+)
3. Parse the CSV with its non-standard formatting (semicolon separator, dates embedded in ship names)
4. Deduplicate records and handle data quality issues
5. Load it into a database
6. Build and maintain this pipeline to run on a schedule

That's 2-4 weeks of engineering work to build, plus ongoing maintenance every time the source format changes. If you're a small team building a maritime product, that's time you don't have.

A simpler approach: query by IMO via REST API

Vessel Class Finder handles the entire pipeline — scraping, parsing, deduplication, storage, and weekly refresh — and exposes the result as a clean REST API. You send IMO numbers, you get structured JSON back.

Register for an API key:

curl -X POST https://vessel-class-finder-production.up.railway.app/register \
  -H "Content-Type: application/json" \
  -d '{"email": "you@company.com", "password": "your-password"}'

Log in to receive your API key:

curl -X POST https://vessel-class-finder-production.up.railway.app/login \
  -H "Content-Type: application/json" \
  -d '{"email": "you@company.com", "password": "your-password"}'

# Response:
# {"message": "Login successful", "token": "jwt...", "apiKey": "your-api-key"}

Query vessels by IMO number:

curl -X POST https://vessel-class-finder-production.up.railway.app/vessels \
  -H "x-api-key: your-api-key" \
  -H "Content-Type: application/json" \
  -d '{"imos": [9200079]}'

Response:

[
  {
    "imo": 9200079,
    "vessel_name": "NORDIC AURORA",
    "class": "DNV",
    "status": "In Class",
    "date_of_survey": "15/06/2025",
    "date_of_next_survey": "15/06/2028",
    "date_of_latest_status": "01/01/2024",
    "reason_for_status": ""
  }
]

You can query multiple IMOs in a single request by passing an array. The response returns all matching vessels.

How the data stays fresh

The pipeline runs on a weekly schedule, pulling the latest data from IACS every Sunday. It uses a staging table approach — new data is loaded into a temporary table first, then swapped atomically — so the API never returns stale or partial results during a refresh.

What you can build with this

• Fleet monitoring dashboards — show class status and upcoming survey dates for a managed fleet
• Risk scoring for marine insurance — flag vessels with suspended or withdrawn class during quoting
• Port state compliance checks — verify a vessel's classification before port entry
• Vessel due diligence tools — include class history in sale and purchase workflows
• Maritime data enrichment — add classification data to existing vessel records in your product

Pricing

The API has a free tier (100 lookups/month) so you can test the integration before committing. Paid plans start at $49/month for 5,000 lookups.

The full API reference and source code are available on GitHub.