Despite the wide selection of inexpensive and sometimes very cheap housing (hostels, hostels) in the center of St. Petersburg, there are also places in the city where you can spend the night for free.
If you plan to spend the night in St. Petersburg (with a one-day transit to the city or hitchhiking), it makes sense to use one of the world or Russian couchsurfing sites, where you can find free accommodation for the time specified by the owner. To do this, you need to register on the website, fill out a questionnaire and send a request-message to people offering accommodation.
Registration is possible both on global sites (interface in English) - Hospitalityclub or Couchsurfing, and on the large Russian-language site Happytrip. In addition, there are communities on social networks: Live Journal, Facebook, VKontakte and on the forums of hitchhiker travelers. It is most convenient to write to several people at once, which will reduce the likelihood of force majeure situations.
Transit passengers can spend the night at the airport. Of course, the waiting room is not the most comfortable place to sleep, but on the benches it is quite possible to stretch out to your full height and sleep. At night, the number of departures and landings is minimized, there will not be very many people at the airport. In addition, all Pulkovo terminals have free toilets where you can wash, put your clothes and yourself in order and freshen up. In addition, airport buildings have free wi-fi internet, sockets for recharging electronic devices, and smoking areas.
Train stations can also be considered a pretty convenient place for a free overnight stay. The waiting rooms are open around the clock, you can sleep on the benches. Toilets at Russian Railways stations are free, but only with a valid ticket in case of transit. In other cases, the cost of going to the toilet is nominal (10-20 rubles). The Moskovsky railway station in St. Petersburg has wireless Internet and sockets, as well as coffee machines with cheap drinks.
In case of a difficult life situation, you can ask to go to the shelter of the Nochlezhka charity organization on Borovaya Street. Here you can not just spend the night and eat, but get legal advice, medical help, advice from a psychologist and a social worker.
Places where you can spend the night almost free
Almost free (from 200 to 400 rubles) you can spend the night in one of the many hostels in St. Petersburg. This price will include not only a bed (a comfortable bed in a room for 4, 6, 8 people), but also the use of a shower, toilet, shared kitchen where you can prepare breakfast, free drinks (coffee, tea) and wireless Internet.