Squareknot was founded by managing director Derek Bond, a former group finance director at Mercedes dealer John R Weir, in association with several established Scottish entrepreneurs.
It seeks to address a funding gap that small and medium-sized enterprises are said to have faced since the financial crash of 2008, while offering benefits to investors such as tax breaks and attractive interest rates.
Mr Bond said: "There is a huge funding gap there, particularly [for] start-up businesses. They have nowhere to turn to just now for funding, other than small grants [which are] available and some awards from Scottish Enterprise and various other places.
"To actually go and raise £150,000 to start a business, there is just nowhere to turn to."
Squareknot has launched with pitches from six companies looking to attract funding of up to £150,000, four of which have developed through Entrepreneurial Spark, the business start-up accelerator.
Mr Bond said he hopes Squareknot will ultimately become the preferred crowdfunding partner for E-Spark, which had previously stated the intention to set up a platform of its own.
A firm seeking investment is Internet Anywhere, the Ayrshire-based satellite broadband provider, which is looking £125,000 in return for a 10% equity stake.
Seetok, the developer of a video message system for the business market, is looking to raise £150,000 in return for 20% of the equity, while Log Six Systems, the inventor of disinfection systems capable of sterilising entire rooms and workplaces, is targeting £150,000 in exchange for 10%.
With other crowdfunding platforms focusing on reward and donation-based funding, or placing restrictions on those who can pitch for loan or equity funding, Mr Bond said Squareknot offers something new.
He added: "Our platform is allowing people to invest in share capital in companies and also lend money to companies. There is not any other platform at the moment that allows a combination of equity, loan and reward funding."
The idea behind Squareknot was sparked by a conversation Mr Bond had with Brian Smillie, described as a "serial executive".
The management team which has been assembled by Mr Bond includes business angel Tom Preston, a former group finance director of the Harry Fairbairn BMW dealer, and Iain Webster, a corporate finance specialist whom Mr Bond worked alongside at KPMG.
On the legal side, he has enlisted corporate lawyer Iain Young, a consultant to Edinburgh law firm Morton Fraser, and on marketing he counts on Brian Smillie jnr.
Mr Bond is the majority stakeholder, having invested "the best part of £200,000" in the venture to date, and the only one currently working full-time in the business.
Squareknot's arrival follows a period of controversy for the crowdfunding concept. Accountancy firm Campbell Dallas warned last month there is scope for SMEs to be "ripped off" unless they understand the risks involved and how loans are repaid.
Mr Bond backed calls for the sector to be regulated and said Squareknot's launch had been postponed from the spring while it gained approval from the Financial Conduct Authority (FCA). It secured approval as an appointed representative of the London-based, FCA-regulated Kessian Capital - a process that took three months and involves Squareknot paying a monthly retainer.