Design a Paste Service

Design a text paste service like Pastebin where users can store and share plain text snippets.

Users should be able to create a paste, receive a unique link, and optionally set an expiration time. The system should support both public and unlisted pastes.

Context

This challenge tests your understanding of object storage, TTL-based expiration, and simple CRUD API design. It's a great warm-up for more complex storage system problems.

Requirements

•Users can create a paste with plain text content
•Each paste gets a unique, shareable URL
•Support optional expiration time (e.g., 1 hour, 1 day, 1 week, never)
•Pastes can be public (searchable) or unlisted (link-only access)
•In your written explanation, include the API contracts for paste creation and retrieval (method, path, and main fields)

Non-Functional Requirements

•Maximum paste size: 10 MB
•Read latency < 100ms (p95)
•Expired pastes should be cleaned up within 1 hour of expiration
•System should handle ~500 new pastes/day

Constraints

•No user authentication required to create pastes
•No editing after creation — pastes are immutable
•No support for binary files, only plain text

Evaluation Criteria

Evaluation criteria and weights will be revealed after you submit your solution. This ensures a fair assessment of your design skills.

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