UK Sponsor Search

A two-part tool for searching UK Home Office licensed visa sponsors, built on open government data.

Built for a personal use case: relocating to London and needing to identify which companies can legally sponsor a Skilled Worker visa.

How it works

DataImporter — a C# console app that:

• Loads the Home Office licensed sponsor list (~140k organisations)
• Loads all 7 parts of the Companies House basic company data (~5.1M active UK companies)
• Matches them in memory using a dictionary lookup for performance
• Outputs a clean SQLite database of ~125k searchable sponsors with full company details

SponsorSearch — an ASP.NET Core web app that:

• Serves a search UI over the generated database
• Supports search by company name, town/city, and visa route
• Returns company number, postcode, incorporation date, sponsor rating, and route

Tech Stack

• C# / ASP.NET Core 10 — web API and data importer
• SQLite — lightweight database for the merged dataset
• Microsoft.Data.Sqlite — direct SQLite access
• CsvHelper — CSV parsing for large government data files
• HTML / CSS / JavaScript — single-page search frontend

Data Sources

• Home Office licensed sponsors list
• Companies House basic company data

Both are published as open data under the Open Government Licence.

Running Locally

Step 1 — Download the data

Download the latest files from the links above:

• Worker and Temporary Worker CSV from the Home Office
• All 7 parts of BasicCompanyData from Companies House

Place them in the same folder and update the desktopPath variable in DataImporter/Program.cs.

Step 2 — Run the importer

cd DataImporter
dotnet run

This generates uksponsor.db — takes around 3-4 minutes.

Step 3 — Run the search app

Update the dbPath variable in SponsorSearch/Program.cs to point to your generated database, then:

cd SponsorSearch
dotnet run

Open http://localhost:5032 in your browser.

Notes

Name matching between the two datasets is exact (case-insensitive). Around 57% of sponsors matched to a Companies House record — unmatched sponsors are still included in search results, just without company number and postcode enrichment. A fuzzy matching approach would improve this and is a planned improvement.