We built an address engine for ourselves. Now it is yours.
Every locum who sets up a shift in Sessional types an address. A practice in Parramatta, a hospital in Townsville, a pharmacy in a town most of us have never heard of. We needed those addresses to be right, with coordinates for travel claims and the boundaries that decide what a locum is eligible for. So we built our own address engine on the Geocoded National Address File, the open dataset every Australian address lives in.
It turned out to be the best thing we own. So we are releasing it for everyone.
Meet Sessional Addresses
Sessional Addresses is a free Australian address API. One key, 10,000 lookups a month, no card. It knows all 16,091,511 addresses in the current G-NAF release, and it gives each one back with the geography attached.
Type "flinders st melb" and you get 88 Flinders Street, Melbourne VIC 3000, its coordinates, and in the same response its local government area, its federal and state electorates, its statistical areas, its remoteness category and its Modified Monash classification. No second request, no boundary files to download, no point-in-polygon maths.
What you can do with it
- Autocomplete an address as someone types, down to the unit.
- Turn coordinates into the nearest addresses, with distances in metres.
- Look up a postcode: its suburbs, state and centroid.
- Ask for every address at a postcode.
- Send messy text like "unit 3/42 wallaby way syd 2000" and get back ranked matches with a confidence score.
- Send a hundred queries in one request, or a whole CSV as a job.
There is a page for every postcode and every suburb in the country too, so if you want to know which electorate covers postcode 2150, or what the Modified Monash category of Dubbo is, you can just read it.
Why we care about the boundaries
If you work in Australian health you already know why. Modified Monash decides rural loadings and eligibility. Primary Health Networks decide funding. Electorates decide who you write to. Remoteness decides half the rules in the NDIS price guide. We needed all of it inside Sessional, and getting it right meant joining the ABS allocation files to every address at load time. Once that work was done for us, there was no reason to keep it to ourselves.
Free means free
The Australian Government publishes G-NAF as open data so that people build things with it. We think the right way to honour that is to make the useful version free as well. The free key is 10,000 lookups a month and it does not expire. Paid plans exist for people who need hundreds of thousands of lookups, and they start at $29 a month with the first month free, which is a fraction of what the established address services charge.
Fast, and honest about it
Autocomplete answers in about ten milliseconds at the server. Postcode, boundary and reverse geocoding lookups answer in under ten. The data reloads with each quarterly G-NAF release, the status page shows exactly which release is being served, and the numbers page shows live usage across the whole service, because a public utility should show its working.
Get a key
Go to addresses.sessional.au, put in your email, and your key arrives in one message. The docs are at addresses.sessional.au/docs, with an OpenAPI description and clients for JavaScript and Python.
Addresses and coordinates incorporate G-NAF © Geoscape Australia, licensed by the Commonwealth of Australia under the Open G-NAF End User Licence Agreement. Boundaries come from the Australian Bureau of Statistics and the Department of Health and Aged Care.