So, leboncoin.fr doesn't like my email alert webapp

No need to, it's just plain old cheap lawyer tactics, it's been around since the beginning of time:

Scare people (i.e. by making them feel they're in danger) and they will do what you want. (Law seems complicated to non-lawyers, so lawyers make use of that, basically by communicating "I'm the specialist and you don't know anything about this domain, so do as I say")

In the case of this story, all I'd suggest the owner of the app, to steer clear of legal issues, is:

a) don't use their name,

b) don't use their logo (or other very distinct parts of their Corporate Identity)

c) re-launch your app (using proxies)

EDIT: On second thought - they don't deserve your exclusive traffic/promotion/value you add. If you keep your app alive, you should multiply your sources (add as many similar sites as possible).

I've seen Frenchmen ashamed to be French when a Le Pen won something somewhere. I've seen Frenchmen ashamed to be French when an anti piracy group pirates a logo. I've seen Frenchmen ashamed to be French when some president felt the need to compensate for something by blowing up a nuclear bomb in the pacific.

Somehow, anecdotally, being ashamed to be born somewhere is a particularly French phenomenon. Why?

France has all the above things, but also a great healthcare system, nice people, a somewhat functional democracy, and many other great things.

There's 60 million Frenchmen. Are you going to be ashamed every time one of them does something wrong? Do you expect them to be ashamed every time you do something wrong?

Instead of shame, maybe it would be more constructive to organize and do something about it. The ivory tower of the French political elite is notorious, but not unsurmountable.

I think leboncoin.fr has the right to ask him to stop the service. but they also have to offer an API to the developers who seek to tweak the service .

LeBonCoin spent like 2M€ in adwords the year they started. I've seen them grow like crazy. I really doubt someone can compete head to head with them today. That would need to be very disruptive or very niche.

is that possible ?

...GOD Yes... welcome back 90's !

And the author is misdirecting the readers by providing a document not related to the claim he makes (TOS infringement vs «droit des marques» infringement).

EDIT/PS «nul ne peut se prévaloir de ses propres turpitudes» means that you cannot prevail your self of any wrongs if it is initially resulting from you not respecting the law. For instance if you build your company on a clearly fraudulent base (parasitism), you cannot claim for any reparation if you are shut down because it is a clear consequence of your actions. As a result, for the lawyer «faisceau de présomption valant preuve» his credibility in front of any juridiction would be voided.

The service can disable their accounts (if any exist) and block their IP's; the service can stop doing any business with them if they don't like the ToS; but the service can ask them to comply, but can't really demand that they comply with ToS, it's not a law nor a contract that they've agreed to.

The cease and desist is NOT about the app. It is about parasitism of the brand.

The use of the API is secondary, but just a part of a proof in a dispute based on the claim of a brand that you are parasiting their immaterial actif called BRAND.

But you don't seem to know how french law works:

* the «raison sociale» of a company has not to be different from another company (ex: Mont Blanc = pen + desert + city), it has to be considered not too close on the naming and on the «secteur d'activité» to be considered parasitism. When you received your kit for funding your society (for instance @chambre de commerce), it is written black on white how the naming of a society should be done. Any brain dead accountant like mine even told me it is wise when choosing a «raison sociale» to first pay a (way too expensive) check into the INPI DB.

* a brand at the opposite of a software is not protected at his divulgation, but at its «territorial» registering (hence INPI and strong advice to make a search at the creation that given your SIRET no company has a name close to yours because else, parasitisme is almost already proven)

* the added presumption of an act are enough to be a proof (faisceau de présomption vaut preuve)

* AND you are dumb enough to make money in the sillon of leboncoin.

Constituting EXACTLY what the french law call parasitism.

I don't support them, but you are legally dumb or dishonest.

I would have respected you if :

* either you had been smart (making money from leboncoin, but registering the brand in a country where leboncoin had not registered (tuvalu? trinidad & tobago)) (remember the territorial part of the brand)

* either you were saying : I know I broke the law, but I think infringing (c) law is stupid because ....

BTW brand are covered by an international convention, so it would have been the same if leboncoin was german, US, or russian.

That's, fairly crazy.