Both are FCA regulated and FSCS protected. The real differences are fees, investment range and how each platform feels to use. Here is the honest comparison.
Fees verified July 2026. Capital at risk. Information, not financial advice.
Fund investors who value guidance, tools and phone support.
Index fund investors who want the lowest possible total cost and are comfortable with a newer app.
| Fee | Fidelity | Prosper |
|---|---|---|
| Platform fee | 0.35% up to £250k (0.20% above); £90/year flat if under £25k without a regular savings plan | £0 |
| Share dealing | £7.50 per online trade | Not applicable (funds and ETFs) |
| Fund dealing | Free | Free |
| FX fee | 0.75% tiered | None on GBP fund classes |
| Stocks & Shares ISA | Platform fee applies | Free |
| SIPP | Platform fee applies | Free |
| Withdrawals | Free | Free |
| Minimum to start | £25/month or £1,000 lump sum | No minimum |
Reviewers highlight helpful phone support and a straightforward transfer process.
The £7.50 share dealing charge and dated parts of the website draw criticism.
Read Fidelity reviews on TrustpilotEarly adopters praise the zero fees and responsive founding team; roughly 84% of reviews are five stars.
The review base is small and some users want more account types and a web version.
Read Prosper reviews on TrustpilotFidelity is a solid full-service choice for fund investors. Fund dealing is free, the ETF and share service fee is capped at £90 a year, and the guidance content is some of the best of the big platforms.
Costs are less friendly if you trade shares often or hold a small account without a regular savings plan. Compare it against AJ Bell if you want similar breadth with lower dealing charges.
Prosper's pitch is the cheapest total cost of ownership in the UK: no platform fee, no dealing fees, and refunded fund fees on a list of mainstream index funds. For a straightforward global tracker in an ISA or SIPP, the all-in cost can genuinely be zero.
The counterweight is maturity. It is a young platform with a small (if very positive) review base and no individual shares. If that trade-off suits you, the price is unbeatable.
A 0.2% fee difference is worth optimising. Knowing whether you are saving enough in the first place is worth far more. Delphina models your pensions, ISAs and investments and tells you where you actually stand.