I worked as a software developer for companies all over the world: Brisbane, Sydney, San Francisco (working remotely from Moscow), The Hague (Netherlands), London then Berlin. The markets are very different in each country.
Moscow is the worst for developers but at least cost of living is low. I feel that Australia is similar to the US in terms of income but it's a less liquid market; low supply, low demand. But the low liquidity of market meant that if you were patient and negotiated well, you could score AUD $900 per day contracts (about $620 USD per day). The cost of living in Sydney is much lower than San Francisco though so I had a really good lifestyle and was still saving money.
In The Netherlands, it was difficult to find contracts above EUR 450 per day (about 500 USD). On the plus side, the government offered big tax cuts to foreigners so you ended up paying less tax than the locals. It felt like I had more disposable income.
London market was tough, it was difficult to find good contracts. I did see adverts for 600 GBP per day in software finance sector but it seemed like I needed personal connections to accesss those. Recruiters were always trying hard to pull me away from the contract market to a lower paid full time opportunity and I felt that I had less negotiating power in spite of having more experience than when I was living in Australia and Netherlands.
Berlin for me was not that great but difficult to say. I moved there because I had already agreed with the company and it was a long term career move. I worked there for 2 years and quit recently. The job market is difficult because they don't usually show salaries or rates on the adverts... This means that companies have more negotiating power and don't care that much about attracting top software engineering talent.
From my experience, countries which pay software developers the most have the best software developers and you can see it in the final products - The experience of using online banking in different countries was interesting.