The reported sale price of one billion dollars no doubt has many developers dreaming of riches, but how do you build a service and scale it to the size and success of Instagram? At least part of the answer lies in choosing your tools wisely.

Fortunately for outside developers, Instagram’s devs have been documenting the tools they used all along. The company’s engineering blog outlined its development stack last year and has further detailed how it uses several of the tools it’s chosen.

Instagram uses an interesting mashup of tried-and-true technologies alongside more cutting-edge tools, mixing SQL databases with NoSQL tools like Redis, and chosing to host its traditional Ubuntu servers in Amazon’s cloud.

In a blog post last year Instagram outlined its core principles when it comes to chosing tools, writing, “keep it very simple, don’t reinvent the wheel [and] go with proven and solid technologies when you can.”

In other words, go with the boring stuff that just works.

For Instagram that means a Django-based stack that runs on Ubuntu 11.04 servers and uses PostgreSQL for storage. There are several additional layers for load balancing, push notifications, queues and other tasks, but overwhelmingly Instagram’s stack consists of stolid, proven tools.

Among the newer stuff is Instagram’s use of Redis to store hundreds of millions of key-value pairs for fast feeds, and Gunicorn instead of Apache as a web server.

All in all it’s a very impressive setup that has, thus far, helped Instagram avoid the down time that has plague many similar services hit with the same kind of exponential growth. (Twitter, I’m looking at you.) For more details on how Instagram looks behind the scenes and which tools the company uses, be sure to check out the blog post as well as the archives.