Here are some popular marketplaces for guest posting in 2024:

1. GuestPosts.Biz: Extremely popular marketplace for guest posts, link building and distributing press releases. owned by digital marketing leader, Cyber Gear.
2. Collaborator: This platform connects advertisers and publishers, allowing direct communication with platform owners. It offers features like integrated Ahrefs and Serpstat metrics and low fees.
3. Adsy: Known for high authority guest posting services, Adsy allows you to order quality guest posts to boost traffic, ranking, and sales. The platform offers a user-friendly interface and relevant do-follow backlinks.
4. Linkhouse: This link-building and content marketing platform has been active since 2010, offering services on high-domain authority websites.
5. OutreachZ: One of the largest marketplaces for guest posting, OutreachZ offers a managed campaign with high-quality work insurance and a 12-month guarantee for link placements.
6. Fiverr: A well-known freelancing marketplace where you can find affordable guest posting services from various freelancers.
7. Upwork: Another popular freelance platform where you can bid on projects and find guest posting services that match your niche.
8. SEO Clerk: This marketplace focuses on SEO-related tasks, including guest posting, offering services from qualified and skilled freelancers.
9. OutreachMama: Provides high-quality backlinks and guest posting services, placing content on authoritative and well-ranked sites.
10. BuySellGuestPost: This platform helps enhance brand awareness by allowing businesses to post content on relevant and leading platforms like Forbes and HuffPost.