Here is a list of the top 10 Instagram scheduler apps for auto-posting on Instagram:

1. Hootsuite: Hootsuite is a popular social media management tool that allows you to schedule and publish posts to multiple platforms, including Instagram. It offers an intuitive interface and a range of useful features.

2. Later: Later is an Instagram scheduling app that helps you plan and schedule your posts in advance. It also provides features like visual planning, hashtag suggestions, and analytics.

3. Buffer: Buffer is another comprehensive social media management tool that supports scheduling posts for Instagram. It offers a user-friendly interface and useful features like analytics and team collaboration.

4. Planoly: Planoly is designed specifically for planning and scheduling content on Instagram. It has advanced grid preview options, hashtag management tools, and analytics to optimize your posting strategy.

5. Sprout Social: Sprout Social offers powerful scheduling capabilities for Instagram along with other social media platforms. It includes features like content calendar, engagement tracking, and user-level analytics.

6. LaterCircle: LaterCircle is an AI-powered post scheduler that automatically optimizes your posting schedule based on the best times to reach your audience on Instagram.

7. Tailwind: Tailwind is primarily known as a Pinterest scheduler but also supports automatic posting on Instagram. It provides features like bulk image upload, hashtag suggestions, and detailed analytics.

8. Sked Social (formerly Schedugram): Sked Social lets you schedule posts in advance and even offers the ability to post directly to multiple Instagram accounts simultaneously.

9. Preview App: Preview App allows you to visually plan and schedule your Instagram posts ahead of time using their drag-and-drop feature. It also offers various filters, editing tools, and insight metrics.

10. Viraltag: Viraltag is mainly used as a visual marketing platform but includes robust scheduling capabilities for Instagram as well as other social media platforms.

Each of these apps has its own unique features and pricing plans, so consider your specific needs and budget when choosing the best one for your Instagram scheduling requirements.