Ask HN: What tool do you use for managing customer software deliveries?

I run a small software agency where we write software for other software companies. I wanted to ask how other companies are managing their communication regarding requirements, timelines, deadlines and progress with their customers, particularly when their customers are software companies.

Ideally, our customers should be able to:

1. Collaborate with us on requirements and communicate deadlines on their side if any. 2. See the timelines for deliveries, including deliverables and how they relate to their requirements. 3. See the current progress on the project. 4. See any blockers or deliverables on their side. 5. Changes made to the requirements, deadlines, deliverables and timelines over time. 6. Have many stakeholders who might have different concerns or share some concerns in a project.

So far, we have tried using a combination of these tools to manage this:

1. Slack: For quick catch-up, queries and updates. 2. Email: For longer or more formal conversation, particularly on the business side. 3. Google Docs: For communicating requirements and commenting on them. 4. Googe Sheets: For timelines and progress.

This requires a lot of manual work and yet it always results in missed issues and lost messages.

What is the HN community using to solve these issues?