Keeping all of that in mind, here’s a closer look at how some of these companies work.

PAVE You must be 18 to join, but the company said there was greater demand for people who were at least in their senior year of college. Given those demographics, close to half the people are using the money raised to repay debt, while others are using the money to pursue a big idea like making films or to further their education. Once the company verifies that individuals are who they say they are, and they pass its financial and credit check, they may create a video campaign and online pitch.

Sal Lahoud, one of Pave’s co-founders, said it used historical guidance based on what the average person had earned in a particular field to estimate a candidate’s future income, which helped it determine how much they were likely to raise successfully. It’s ultimately up to the prospects to decide what percentage of their earnings they are comfortable signing away for the next 10 years, though it can be no more than 10 percent of their annual income.

There is no cap on the amount repaid to investors, but prospects can always decide to pay their backers five times the original amount, unless other terms are set. “If you are doing amazing, why should the people who invested in you early on not participate?” Mr. Lahoud asked. “We built a contract that balances both sides very well. The investors take full downside and full upside.”

Borrowers don’t pay anything if annual income falls below 150 percent of the federal poverty line.

Pave takes its share, too: 3 percent of the amount the individual raises, and it charges a 1.5 percent servicing fee on payments made to the investors, who are estimated to earn about 5 to 8 percent on their investment.

So far, more than 4,000 prospects have applied to the program, with more than 1,000 backers. But the service opened to the public only six weeks ago. About 30 people have either received all of their funding or are still currently raising money, for a grand total of $550,000. About 130 more prospects have been invited to start campaigns, which will be introduced on the Web site over the next few months.

UPSTART Though the company plans on opening the program to more people, right now it’s accessible only to college seniors and people who graduated from a four-year college or a graduate program within the last eight years. You also need to be in reasonably good shape creditwise, meaning you need a FICO score of at least 640. (Having no credit history is acceptable).

The maximum candidates can share is 7 percent of their projected annual income (over 10 years), which is calculated using its own model.