Are there any future plans to enable a filtering option on the /multidomain search API endpoint (possibly by breach name)? My company is getting to the point where the xlsx/json response is too large and the request times out.

Thirded - to be able to search by breach would at least mitigate the impact of not being able to pull through historic data.

I would like to second this--having the option to query by breach or just a single domain would be very helpful rather than getting no results about any breaches for any domains we monitor.

ok, I understand regarding the threshold. What about the suggestion to implement the possibility to filter by specific breaches or within a date/time window? This would most likely avoid hitting the threshold in almost all cases.

No change, there's still a threshold beyond where I simply can't return the data within a reasonable amount of time without impacting the service.

Any news on this issue? There were a few breaches in the last months affecting larger numbers of our users and we are not able to download the data sets due to the large data set error.

I will stay tuned. Thanks for looking into this and for this great service you are providing with HIBP!
Another optimization could be to allow filtering by specific breaches and/or date range for the multi-domain search so the result set of a query can be drastically reduced.

I'll leave this idea sitting here as it's something I'd like to optimise in the future, but this is also only an issue when there's a huge result set due to either the number of domains or the number of email addresses on them. At some point, there has to be a cut-off on execution time. That said, I do think I can optimise the query by asyncing the more of the Table Storage requests. Stay tuned.

Exactis breach, of course, not avectis :-)