We run Stripe Radar and 3-D Secure when adding a card (before first use), which filters out a lot of obvious fraud (and 3DS often shifts liability to card networks in many regions).

The balances are not settled just at the end of the month. Each customer has a "maximum owed limit", which starts low (currently 10 USD) and grows with successful payments (up to 30 USD currently). The customer is charged as soon as they hit that limit (with some grace to allow for continued use).

Idempotency keys are on the near-term roadmap. Access tokens do not currently expire; however, they can be revoked by the customer at any time.

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franga2000 3 days ago | parent [-]

I really like the growing maximum owed limit idea and it would be really interesting to also make it possible to set an auto payment threshold lower than it.

The idea being something like "charge at X € owed but let it go up to N*X € if a payment fails before suspending service" where the N scales with something like the number of paid invoices or even total past spend.,

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strnisa 3 days ago | parent [-]

The primary objective of the max-owed limit is to cap per-customer risk.

If you are suggesting that the max-owed limit is actually N×X, then that would multiply worst-case exposure by N, which is undesirable.

If you are suggesting that we charge the customer when they owe X while their max-owed limit is N×X, this would be worse for the customer, since they would pay `N × (X × variable_rate_fee + fixed_rate_fee)` instead of `N×X×variable_rate_fee + fixed_rate_fee` in payment processing fees.

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franga2000 3 days ago | parent [-]

If your payment processor takes a per-transaction fee (not all do) then yes, this is a slightly worse deal for the customer. However, I think this would still be a good choice to give them, even if many would probably not chose it in order to save a few cents.

If I burn 1 € per day and my max owed based on whatever risk assessment is 20 €, I can set my payment treshold to 15 €, meaning if a payment fails, I have 5 days to fix it and settle the debt before you suspend my access. If the trigger amount is the same as the max owed, I have zero time (well, presumably there is already some wiggle room for the time it takes to process the transaction).

	▲	strnisa 3 days ago \| parent [-]
		I see what you mean — yes, this could be useful to some customers. We already implement a small grace amount above the max-owed limit that allows for continued service; your idea would essentially allow the customer to increase the default grace amount.