May 29, 2025

1.1 Million: the Tech Powering the Record-Breaking TCS London Marathon Ballot

Rob Fearn
B2B & Product Marketing

The 2026 TCS London Marathon ballot has officially surpassed one million applications: a historic world record for the most popular marathon on the planet. For the first time, in collaboration with London Marathon Events, we’re sharing key facts and figures from behind the scenes of the ballot for the world’s most sought-after marathon.

World-Class Stability at Unprecedented Volume

Opening at 09:00 on launch day, the ballot saw more than 45,000 applications in the first hour alone (triple the volume seen in 2025). Peak traffic surged from 2,000 to 16,000 simultaneous users within minutes. Most impressively, during this initial spike, the system queued just 400 people - for a maximum of 8 seconds.

Across the entire period the ballot was live, queue times remained remarkably low: an average of just 42 seconds. Traffic spikes aligned with national media coverage, for example a BBC One mention on Day Two more than doubled live user sessions from 6,000 to 14,000 in minutes. The platform remained fully responsive throughout.

An Upgraded Platform at Half the Cost


While this year’s ballot infrastructure was built to withstand unprecedented load, Let’s Do This also implemented key backend upgrades, including:

- Performance-tuned backend code and load balancing

- Deployment on lower-cost, high-efficiency resources

- Database optimizations to reduce strain during peak usage


Together, these changes not only improved performance - with a 112% year-over-year capacity increase - but also delivered a 56% reduction in infrastructure costs compared to 2025.

Encouraging Shared Experiences


To boost social virality, the 2026 ballot included a new social sharing modal. Once applicants completed their entry, they were shown a low-friction pop-up to encourage friends and family to apply as well.

This small feature delivered a meaningful uplift: 13% of applicants used the sharing tool, directly driving 6% of total ballot entries.

The Future of Participation

Since Let’s Do This began powering the TCS London Marathon ballot three years ago, numbers have steadily grown. The 2026 ballot marks a 36% increase from 2025 and nearly double the 2024 total of 578,304.

The new 1 million plus application milestone represents more than just a record-breaking moment - it’s the latest signal that the sustained growth we’ve seen in the industry is showing no signs of slowing. Moreover, with more applicants than ever before set to miss out on a place in the 2026 marathon, the running industry as a whole is set to make the most of a new generation of runners inspired to find more amazing events.

Hugh Brasher, CEO of London Marathon Events, said:
“Our ambition is to inspire activity in people of all ages and abilities and these astonishing numbers show how the TCS London Marathon does that and how many people want to be part of it. We’d like to thank our partner Let’s Do This for delivering a seamless operation for this record-breaking ballot.” 

Sam Browne, Let’s Do This CEO added:
“Marathon Week is probably the most special (and busy!) period on our calendar each year. Full credit to the teams at both London Marathon Events & LDT who worked tirelessly together to make this 1.1 million milestone happen - it’s a hugely important moment for us as a business, and further motivation in our mission to inspire people to get together offline.”

About Let's Do This

Let’s Do This is a leading registration and technology platform for events, helping organizers grow through powerful registration, event management, marketing, and data tools. As the first platform built for social registration, Let’s Do This multiplies word-of-mouth growth through teams, invites, referrals, and an app designed to help people discover and engage with events in their network.

Let’s Do This is the exclusive partner to the world’s most popular marathon (TCS London Marathon – London Marathon Events), the world’s largest half marathon (AJ Bell Great North Run – Great Run Company), and the world’s largest 10k (AJC Peachtree Road Race – Atlanta Track Club), as well as innovative brands like Ragnar Events and Diplo's Run Club. Backed by over $80 million from top-tier investors including Y Combinator, Craft Ventures, and Headline, as well as athletes like Serena Williams and Usain Bolt, LDT is building the future of participation - together.

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