Earning bitcoins for free is generally difficult, as acquiring bitcoins requires active participation or an investment of time, energy or money. However, here are some potential methods for obtaining bitcoins without spending any money:

Bitcoin faucets: faucets are websites that distribute small amounts of bitcoins free of charge in exchange for simple activities such as viewing ads or solving captchas. However, earnings are generally very low.

Bitcoin  games: Some online games allow you to earn bitcoins by playing. These games may include lotteries, role-playing games or games of skill. However, it's important to exercise caution when it comes to online games, as some can be fraudulent.

Referral programs: Some cryptocurrency-related service websites or applications offer referral programs. You can earn bitcoins by recommending these services to other users who sign up and make transactions.

Paid micro-tasks: Some online platforms offer bitcoin-paid micro-tasks. These may involve completing surveys, testing applications or performing small online tasks.

Airdrops: Airdrops are free distributions of cryptocurrencies, including bitcoin, carried out by projects or startups to promote their token. You can participate in airdrops by registering on specific platforms and fulfilling the required conditions.

It's important to note that most of these methods can generate very limited gains and can be very time-consuming. If you want to invest in BTC  in a meaningful way, it's generally best to buy bitcoins on reputable exchange platforms or explore other ways of investing in crypto.