In a political movement, the main source of costs is the organization of the movement itself (members, committees, events). It is perfectly normal as it is the core of the party, but it is really difficult to decrease these costs. In classical parties, this organization required to have a physical place in thousands of cities in France.

What I meant in the article was that our budget was way smaller than the one of other parties. That is the reason why we relied mainly on Internet since the beginning to create committeess and organize events.

This being said, the "small" budget we had was not that small if you see it as an individual: we had several million euros coming from donations and loans. This was not enough to have physical places in France but it was largely enough to create a high-end platform instead.

Technically speaking, the hosting and the different services we use costed us around 8000 euros/month at the end of the campaign, including the DDoS attacks mitigation (which did indeed increase our costs). The website development itself is very difficult to estimate as it was made both by volunteers as me and by external companies.

I also would like to add that the cost of development would have been much higher if we had relied only on external companies. The flexibility required by a presidential campaign forced us several times to develop complete features in a few hours and that would have been difficult with a classical company only, requiring specific contract and limiting our possibilities. I think one of the reasons why the project went really well was because of the synchronization between motivated volunteers (highly flexible work time) and external companies (proper high-end quality code).

I'm sorry, the accounting is meant to be public, but I can't find it. It might be too early, or google is failing me.

On a related note, the total budget for the candidates had to be less than 17M€ all included before the first round (then they could spend 5.6M€ more for the second round). A lot of that goes into organizing rallies.

edit: I guess they are meant to be here http://www.cnccfp.fr/index.php?art=584

Accounting breakdown for the 2017 election is not yet available, apparently. This page list accounting breakdown for the 2012 and 2007 presidential elections: http://www.cnccfp.fr/index.php?art=720

I also would be curious to know the production and operating costs for a website of this kind.