Milestone payments indeed provide a structured, risk-minimized payment approach for both brands and influencers in influencer marketing. Here are a few influencer marketing platforms that support milestone-based payments:

1. Grin: Grin offers a campaign management system with a focus on ecommerce businesses. They have integrated payment options that can accommodate milestone payments, enabling brands to release funds at specific project stages.

2. AspireIQ: This platform helps to manage influencer relationships and has capabilities for setting up structured payments, which can include milestone-based schedules.

3. CreatorIQ: CreatorIQ uses a campaign-centric model where milestones can be set within a campaign. This framework enables brands to assign payments to specific stages or deliverables.

4. Flinque: Flinque’s platform supports customizable payment schedules, including milestone-based payments. This way, brands and influencers both have transparency and control over their payment process.

Remember, the suitability of a platform doesn’t solely depend on the ability to make milestone payments. It’s also about other features, such as campaign planning, audience analytics, or the level of customer service. These factors must align with your team’s specific needs to achieve the best results out of your influencer marketing campaigns.