Use trading to earn platinum.
Unlike most free games, Waframe's premium currency is tradable and has thus become the backbone of the economy. The majority of the items in the game are free from trade restrictions, which means that if you're willing to work on collecting something, someone will likely want to buy it. You will need to know how to trade before you can start trading for Platinum, so be sure to check out our trading guide if you are unfamiliar with this aspect of the game. If you are, then Platinum is relatively. easy to grow.
First of all, the relics will be your best friend. Definitely check out Warframe.market to see which Prime Coins are currently in vogue and are not Vaulted (Vaulted Coins cannot be acquired out of commerce, or until they are Vaulted), and see how to mine them in. better via Zone Tenno. Players will pay one good dish for a full set of blueprints, and over 20 dish for 5 random pieces of "unwanted" pieces (a random mix of main pieces, or so). Even if you don't complete a set, or don't want to farm the rarer items into Relics, you can group five main pieces together and flip them over for a quick plaque.
Of course, that means you will have to collect Relics to break them. Endless missions are generally a good way to craft random relics, although you can use the Tenno area to hunt down any you want. Jump into a 20 minute survival or 20 wave defense to collect a few. As a bonus, any Relics you grab and don't use will eventually become stooped, which can see their goods go up in price. It's not a guarantee, but it does mean that anything you don't focus on may still net you a little bit of advantage.
Plus, mods are a solid way to earn extra trays. As a general rule, the rarer a mod, the more it will sell. This is also true if you transfer endo into the mod and set it to max: players will pay more dish for maximized mods than for mods without level. You can use Warframe.market to see which mods are available to you and are selling well, then use Tenno Zone to track them down.
If you want to earn a lot of money, you need to complete The War Within and start farming Rivens. Rivens are powerful random mods, but they take time and effort not only to farm, but to revive. This method will require more homework, grinding, and patience, but can result in massive amounts of dish. At the height of the Meme-ing Strike meta, there was Rivens for 4000 Platinum: that's a few hundred dollars worth of flat there! While it has mellowed, you can still sell Curvy Rivens for a thousand or more dishes. Riven Market is a good place to see what people are looking for and to check prices if you choose to enter Riven Trade.
This is how you can earn Platinum for free. This will require some work on your part and you will need to trade with other players. Fortunately, there are both simple and complex ways to fill your chests, and it will all depend on how much work you want to do. Of course, I like to support DE with a purchase here and there (a 70% coupon usually does the trick), but being able to set a goal and grow my dish on my terms is a good way to avoid to spend money.
