System designLast reported Aug 2026
Design a Multi-Tenant AI Gateway
Design a policy-enforcing gateway that routes isolated tenant traffic across model providers while supporting streaming, quotas, fallbacks, and durable usage records.
Open practiceDecagon interview practice
Decagon interview questions and coding practice Start with verified evidence.
Practice from 2 Decagon-tagged public coding problems, organized only by the stage, topic, difficulty, and recency metadata FastPrep can verify. The broader public catalog also includes 1 system-design exercise.
- Catalog
- 3 public practice assets (2 coding)
- Start here
- Use the stage named in your invitation
- Evidence
- Phone metadata, shown in context
Phone practice path
Phone Screen
Practice solving while explaining assumptions, tradeoffs, and complexity. Problems are ranked by repeated public catalog sightings.
2 Decagon-tagged Phone Screen problems available.
| Company | Problem | Difficulty | Public evidence | Action |
|---|---|---|---|---|
DEDecagon | Versioned Recipe Shopping CartDesignHash Table | Hard | 2 public reportsLast reported Aug 2026 | Practice |
DEDecagon | Nested Recipe Cart TransactionsDesignHash Table | Hard | 1 public reportLast reported Jul 2026 | Practice |
01 · Preparation plan
Turn versioned carts, nested transactions, and AI gateways into a deliberate practice loop.
Decagon's evidence centers on transaction boundaries: compare rollback in an in-memory cart with tenant isolation and durable usage accounting in a streaming AI gateway. Catalog labels guide practice but do not promise a current or universal hiring loop. This is a suggested practice sequence, not the employer's interview process. Your invitation and recruiter guidance remain the source of truth.
- 01
Practice Versioned Recipe Shopping Cart
Use Versioned Recipe Shopping Cart to rehearse versioned mutations and rollback. Keep the exercise's published contract separate from assumptions about Decagon's current interview process.
- Restate the exact input, output, and constraints for versioned mutations and rollback.
- Explain the data structure and complexity before completing the implementation.
- Test a boundary case, a repeated-value case, and the smallest valid input.
- 02
Practice Nested Recipe Cart Transactions
Use Nested Recipe Cart Transactions to rehearse nested transaction stacks. Keep the exercise's published contract separate from assumptions about Decagon's current interview process.
- Restate the exact input, output, and constraints for nested transaction stacks.
- Explain the data structure and complexity before completing the implementation.
- Test a boundary case, a repeated-value case, and the smallest valid input.
- 03
Practice Design a Multi-Tenant AI Gateway
Use Design a Multi-Tenant AI Gateway to rehearse tenant isolation, streaming, and provider fallback. Keep the exercise's published contract separate from assumptions about Decagon's current interview process.
- Set concrete scale, latency, and correctness requirements for tenant isolation, streaming, and provider fallback.
- Draw ownership boundaries and the data path before choosing components.
- Exercise one overload or dependency failure and explain the recovery path.
02 · Broader technical practice
Practice beyond standalone coding questions.
These public Decagon-tagged exercises cover additional technical formats. They are included only when a verified catalog record and a crawlable practice page both exist.
03 · Evidence boundary
What “Decagon interview questions” means here.
It means practicing transferable implementation, testing, and technical reasoning with public catalog assets FastPrep tags to Decagon. It does not mean FastPrep has access to the company's assessments or any private interview bank.
Repeated public sightings and last-reported dates can help you prioritize practice, but they cannot predict the questions, format, or platform in a specific interview.
- Only Decagon-tagged FastPrep catalog problems appear above.
- Stage labels and report dates remain visible as context.
- No official, private, leaked, or proprietary questions are claimed.
04 · Plain answers
Decagon interview practice questions, answered plainly.
This page owns technical-practice intent for Decagon. Hiring activity, timelines, and market signals remain on the separate hiring-insights page.
01What evidence supports this Decagon interview practice page?
The launch review verified 2 coding exercises, 1 system-design exercise (3 total public practice items). The strongest reviewed themes are versioned mutations and rollback, nested transaction stacks, tenant isolation, streaming, and provider fallback. Counts and report labels can change, so use this as a focused practice library and follow your own invitation for the current format, timing, and permitted tools.
02Is FastPrep affiliated with Decagon?
No. FastPrep is an independent interview-preparation product and is not affiliated with Decagon. The page uses FastPrep's public practice catalog and does not claim official, private, leaked, or proprietary employer questions.
03How are Decagon problems assigned to interview stages?
Stage labels come from FastPrep's public problem metadata. A problem can carry more than one reported stage, and hiring processes can change by role, level, location, and date. Treat the labels as preparation context, not a guarantee.
04Which Decagon interview stage should I practice first?
Start with the stage named in your invitation or recruiter message. If no stage is known, use the largest available set to build general problem-solving fluency, then rehearse explanation and testing separately.
05Does this page predict the Decagon interview process?
No. Public catalog counts, stage tags, and last-reported dates can help prioritize practice, but they cannot predict a specific interview's questions, sequence, timing, or platform.
Your next stage, made concrete
Pick a problem. Solve it end to end.
Start with the stage named in your invitation, then use public evidence as context—not as a promise of what you will be asked.
Open the practice set