Are there costs involved in publishing in JMIR journals, what are your fees?

Yes, there are fees for most (but not all) JMIR journals and most (but not all) article types.

Most authors pay these costs from their grant money, from the same funding envelope from which they would for example pay conference travel and fees. Some universities, institutions or departments have institutional membership arrangements with JMIR Publications, in which case the APF can be waived. Other institutions may have institutional open access funds, for example the signatories of the Compact for Open Access Equity. (for details see also How are JMIR authors funding the publication costs?).

The general cost for publishing in our journals is the total of

Submission Fee (only J Med Internet Res, US$90 until July 2019)
+ Article Processing Fee (for most but not all journals, price varies by journal, see JMIR Fee Schedule)
+ Fast-Track Fee (optional, US$450, available for all journals) (How to fast-track (expedite) a paper and what are the benefits?)

Submission fees are no longer charged as of July 2019
most JMIR journals have an Article Processing Fee (APF) (sometimes called Article Processing Charge or APC), payable only in case of acceptance
for all JMIR journals, authors can expedite the peer-review and publishing process by paying an optional Fast-Track Fee.
for a full fee schedule of JMIR journals click the Fee Schedule link in the footer of each JMIR journal homepage (see screenshot below)

Exceptions (waived fees):

sometimes JMIR may publish Theme Issues which are sponsored by third parties, in which case the APF does not apply. Please watch our announcements for calls for papers which specifically say that it is a sponsored theme issue.
There is currently no fee for letters to the editor. However, such a letter must specifically critique or comment on a previous JMIR article. We do not publish "Research Letters" - these must be submitted as original (brief) articles and the APF applies (if the paper is short, there may be a discount)
There is no fee for the article type Personal Perspectives if written by a patient
If your research unit, department or university has set up an institutional membership with fee waivers with JMIR Publications, the APF/APC may be discounted or waived
some (newer) JMIR journals may not have any fees

For more information on publishing without paying an APF see I don't have any grant money - how can I publish in JMIR?

Special Fees in Exceptional Cases for Additional Editorial Work