A guide to exploring ownership, control, and corporate structure faster – and with more confidence.
Understanding how companies connect has become a critical part of modern business intelligence. For assessing risk, managing compliance, or researching markets, you need to know more than just a company’s name and registration number – you need to know who owns what and how those entities relate.
That’s exactly what the OpenCorporates API + Relationships File enables. Together, these two tools give you a complete picture of corporate networks – from verified company data to ownership hierarchies and control structures – all grounded in official, open sources.
This guide explains how the combination works, why it’s valuable, and how you can start using it to make better decisions with connected corporate data.
Why corporate relationships matter
A company rarely operates in isolation. It might be part of a larger group, owned by a parent company, or controlling subsidiaries in other jurisdictions. Understanding those links is essential for:
- Compliance & due diligence – Identify beneficial owners and corporate control chains for KYC and AML purposes.
- Supply chain & vendor risk – See how your suppliers connect globally to manage exposure and reputational risk.
- Investigations & research – Follow complex ownership structures to uncover control and influence across borders.
- Market strategy & growth – Identify related entities or group structures that reveal new opportunities.
Each of these scenarios depends on one thing: clarity of relationships. And that’s where OpenCorporates’ combined tools come in.
What the combination offers
The OpenCorporates API and Relationships File are designed to complement each other. Here’s what each does – and why using them together makes your analysis faster, easier, and more powerful.
| Feature | OpenCorporates API | Relationships File | Together |
| Purpose | Real-time company lookup and verification | Bulk mapping of corporate links | From single entity to complete network |
| Strength | Precision and reliability | Scale and structure | Accurate, network-level insight |
| Best for | Identifying the right company | Exploring ownership, control, or subsidiaries | Seamless workflow: verify → expand → map |
| Data Source | Official company registers | Derived relationship data from official filings | Combined context for richer intelligence |
The API gives you verified company information – names, identifiers, officers, and filings – ensuring you start from the right entity.
The Relationships File builds on that foundation, showing how companies are linked by ownership, shareholdings, or structure.
Used together, they give you the power to explore corporate hierarchies with both accuracy and scale.
Step-by-step: How to use them
Let’s walk through how to map a corporate network using OpenCorporates.
1. Identify the company
Start with the OpenCorporates API. Search for the company you’re interested in – for example, OpenCorporates Ltd. Retrieve its official details, including jurisdiction code and company number. These identifiers act as your anchors for everything that follows.
2. Verify the details
Once you’ve found the company, use the Company Info endpoint to confirm it’s the right one. You’ll get verified information: registered address, officers, status, identifiers, and filings. This ensures your analysis begins with clean, authoritative data.
3. Expand the network
Now switch to the Relationships File. Using the company’s jurisdiction code and number, find all related entities – both upwards (parent or owner) and downwards (subsidiaries, branches, or affiliates).
Each row in the Relationships File represents one connection between two entities:
- Subject = typically the controlling company or individual
- Object = typically the company being controlled or linked
By following those relationships, you can quickly trace the full structure around your target.
4. Map & analyze
Continue expanding as needed. Each new company identified can be cross-referenced back through the API for detailed information, creating a verified, connected web of data. Repeat this process until you’ve mapped the ownership or operational hierarchy to your desired depth.
Inside the Relationships File
The file itself is structured for usability and scalability. Each record includes:
- Relationship ID
- Subject and object company numbers and jurisdictions
- Relationship type
- Ownership or voting percentage (where available)
The relationships fall into four main types:
- Control statements – show declared ownership or voting rights.
- Subsidiaries – parent–child corporate links.
- Branches – local presences tied to a head office.
- Share parcels – partial ownership or investment holdings.
This makes it easy to distinguish between ownership, control, and operational relationships.
Why it’s efficient and scalable
If you’ve ever tried to trace corporate connections using APIs alone, you know it can take hundreds (sometimes thousands) of calls to uncover all the relationships around a large company. That’s time-consuming – and unpredictable in cost.
The Relationships File solves that. It gives you the full picture upfront – a structured, bulk dataset of connections you can explore instantly. When paired with the API’s precision, it becomes a workflow that’s both accurate and efficient:
- Use the API for live lookups and confirmation.
- Use the Relationships File for analysis at scale.
When to use this combination
You’ll get the most value from the API + Relationships File if you need to:
- Map complex corporate hierarchies
- Automate due diligence workflows
- Analyze ownership networks across jurisdictions
- Build relationship visualizations or risk models
- Research global corporate structures at scale
Summary
The OpenCorporates API + Relationships File gives you the full story:
- The API ensures you’re expanding from the right entity.
- The Relationships File shows you everything around it.
Together, they transform company data from isolated records into an interconnected network of ownership, control, and influence.
It’s fast, accurate, and transparent – and it helps you make better decisions, backed by open, verifiable data.
Learn more about the OpenCorporates API + Relationships File →
For more information
Learn more about how OpenCorporates’ data can help you understand corporate structures and manage risk. Reach out for a demo or explore our services.
