From Spotify and Apple Music to Netflix and Amazon Prime, huge chunks of the media distribution world are moving from paid downloads to monthly subscriptions. But since the early days of digital comics and graphic novels, most have been sold on a per-unit basis.

Services such as Marvel Unlimited, Scribd and ComicBliz now offer fans access to content rather than downloads. But it’s still too early to know whether these services can change consumer habits. Here’s a look at the principal players offering comics on the subscription model.

Marvel Entertainment has offered the industry’s most comprehensive subscription program, Marvel Unlimited, since 2007. The service gives readers access to over 17,000 titles for $9.99 per month, including comics from the earliest days of the company up to six months behind current issues. Access also includes popular Star Wars titles as well as the company’s wildly popular superhero universe.

“Marvel Unlimited is a very important segment of our overall digital strategy,” said Daniele Campbell, Marvel’s v-p of digital development and customer relations management. “It compliments our already growing digital business and provides another way for our customers to consume our content.” Campbell said the service has seen strong growth that tends to spike around the announcement of new cinematic or television properties.

In October, Marvel’s parent company, Disney, launched a new digital subscription service called Disney Life. Though Disney Life is currently only available in Europe and does not include Marvel or Star Wars properties, CEO Bob Iger signaled that Disney’s long term subscription strategy was to go directly to consumers and “not through middlemen.”

“We’ve been selling directly to consumers in the Marvel digital comics world for a long time with Marvel Unlimited, the Marvel Comics app and Marvel Comics’ webstore,” she said, echoing Iger’s comments. “The digital comics landscape is a complement to print and we view the digital ecostystem as a way to quickly reach new fans who may have connected with our IP though our films, television, or games.”

Archie Comics, which has also offered a web-based digital comics subscription service for a while, just relaunched its app on the Madefire digital publishing platform offering access to all its content. Archie CEO Jon Goldwater said the new Archie app offers customers a variety of buying choices, including single issue sales as well as Archie Unlimited, a digital subscription service for $7.99 per month that provides access to thousands of backlist and new titles.

Things are also picking up on the distributor side. Scribd, the digital document distributor that launched a subscription program for e-books in 2013, expanded to comics in February 2015. The service currently offers more than 10,000 comics and graphic novels from publishers including Marvel, IDW/Top Shelf, Boom! Studios, Valiant, and Dynamite. Earlier this month, Scribd discontinued individual comic download sales and moved to offer its comics content via subscription only.

That could be a two-edged sword. All things being equal, comics take less time to read, which means the average comics fan is likely to consume a lot more content from an “all you can eat” service than people who read prose books. Depending on how publisher contracts are structured, high-frequency comics readers could end up costing a site more than the cost of the product, a problem encountered earlier this year with Scribd’s romance category. Scribd has since dramatically cut the number of romance titles it offers.

While the company declined to specify the volume or revenue share of digital comics in Sribd’s overall business, Andrew Weinstein, v-p of content acquisition, said “Comics readers are some of the most intense users on Scribd.” Asked if Scribd saw comics as a growth opportunity in the coming year, he said: “All of the genres on our site serve a unique community and are areas for growth.”

ComicBlitz, which launched a comics-only subscription service in October, is the newest subscription player, offering unlimited access to a library of comics content for $9.99 per month. Publishers include Dynamite, Valiant, ActionLab, Xenoscope, Aspen, and kids publisher Learner Books’ Graphic Universe titles. “We currently have over 2,500 titles available, growing to 3,000 by December,” says CEO Jordan Plosky. “We are committed to growing our inventory every month” on terms he emphasizes are sustainable for both ComicBlitz and publishers.

Plosky says the company invested significantly in developing an app interface optimized for reading comics and graphic literature, and is not just a general-purpose reading app. “We believe our advantage comes down to user experience,” says Plosky. “We’re a niche product focused on what comics readers want.”