Vanguard reported a 130% increase in users in the year to March 2021, and AJ Bell Youinvest saw a 30% increase in registrations in 2020. A third of new investors were people under the age of 30.

Which? surveyed nearly 2,000 of its members and analysed 11 online DIY investment platforms based on customer ratings and costs.

Rankings were based on six criteria: online tools, customer service, investment information, whether it met the customer’s needs, value for money and customer score.

The best DIY investment platforms

Vanguard and AJ Bell Youinvest came out on top in Which?’s survey, with customer scores of 77% and 72% respectively.

Vanguard was praised by survey respondents for being ‘straightforward’ and ‘efficient’, and was the only platform to receive five stars for value for money.

While there is a limited selection of investments (75 of its own funds), fees are some of the lowest on the market at just 0.15% a year (capped at £375 a year for accounts over £250,000). Vanguard does not charge for trading funds and its funds have low ongoing costs, at 0.2% on average.

AJ Bell Youinvest offers a larger range of investments, with more than 2,000 funds, shares across 24 stock markets and a variety of other assets. Users also receive access to a more extensive range of investment information, including guides, tools and the ability to see funds ranked by their Morningstar Rating.

Customers praised AJ Bell Youinvest’s ‘easy to navigate website’ and ‘excellent range of investment opportunities’. AJ Bell costs more than Vanguard, but remains cheaper than many competitors.

Investors will pay 0.25% on the first £250,000 of funds, then 0.1% on any amount between £250,000 and £1m. To buy or sell a share, investment trust, exchange traded fund or bond you’ll pay £9.95 and 0.25% to hold them, capped at £3.50 a month.

For larger portfolios, Which? found that Interactive Investor, which had a customer score of 68%, is a cost-effective option. Fixed monthly fees, ranging from £9.99 to £19.99 depending on the plan, make it an attractive proposition for investors with more than £50,000 in their portfolio.

Another platform worth considering for investors with larger portfolios is Halifax Share Dealing, which had an overall customer score of 63%. Its flat £36 annual platform fee is the cheapest on offer for large portfolios. However, Which? members complained about a lack of information on investment opportunities.

Less popular investment platforms

Hargreaves Lansdown, the biggest platform featured in the survey, finished sixth with an overall customer score of 66%. Its annual fee of 0.45% makes it pricier than many competitors for funds. Some survey respondents said they lost trust in Hargreaves Lansdown after it continued promoting the Woodford Equity Income fund on its Wealth 50 best buy list until the day the fund was suspended in June 2019.

Finishing bottom of the pack for the fourth year in a row was Barclays Smart Investor, with a ‘disappointing’ overall customer score of 48%.

Some survey respondents’ dissatisfaction stemmed from the provider switching its service from Barclays Stockbrokers to Barclays Smart Investor in 2017. Others were disappointed by high charges, a limited range of investments and a ‘complicated’ website.

Jenny Ross, Which? Money editor, said: “Whether you’re a new or experienced DIY investor, your choice of investment platform is crucial, as both costs and the level of service on offer can vary considerably.

“In addition to platform charges, don’t forget to take into account the fees for buying and selling investments, especially if you plan to trade regularly. If you find you’re paying more in charges than you need to, it could be time to switch.”