ElevenLabs Software Engineer Interview Guide

The 60-second brief

A Software Engineer at ElevenLabs works at the intersection of high-throughput distributed systems, real-time AI audio synthesis, and product execution. As a core member of the engineering team, you are responsible for building infrastructure that streams AI-generated voice and audio with sub-millisecond latent boundaries to millions of globally distributed concurrent users. Whether you are scaling low-latency streaming pipelines, designing APIs for SDK integrations, or architecting backend platforms to handle complex workflows like automated voice dubbing, your work directly defines the reliability and responsiveness of the world’s leading research-driven AI audio platform. Engineering at ElevenLabs requires a distinct blend of deep algorithmic efficiency, practical Python and TypeScript execution, and strong product intuition.

This guide is scoped to a Software Engineer candidate at ElevenLabs.

Focus areas

• SQL
• React
• Live coding (interactive implementation)

The ElevenLabs interview process

ElevenLabs candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Online Screening

Initial assessment focused on algorithmic efficiency and core language proficiency.

What to demonstrate

• Initial assessment focused on algorithmic efficiency and core language proficiency
• Depth in SQL

How to prepare

• Answer aloud and timed: Implement a sequence tracking algorithm where every number is generated by adding the sum of its digits to itself. Write a method to calculate the exact join point where two sequences starting from different numbers intersect.
• Answer aloud and timed: Simulate a multi-step grid event system where directional wind shifts affect the physical state and placement of leaves on an $N \times M$ matrix, returning the total remaining leaves after all wind events execute.

Recruiter Conversation

Discussion to align on expectations and compensation.

What to demonstrate

• Discussion to align on expectations and compensation
• Depth in SQL

How to prepare

• Be able to walk your CV end to end in two minutes, and say why this company specifically.
• Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Rounds

Involves live coding, practical component design, and system architecture discussions.

What to demonstrate

• Involves live coding, practical component design, and system architecture discussions
• Depth in SQL

How to prepare

• Answer aloud and timed: Given an unsorted stream of integer elements, merge sorted lists while removing duplicates in optimal time and minimal auxiliary space.
• Answer aloud and timed: Write an asynchronous database processing engine in Python or TypeScript that batches inbound streaming read/write requests without blocking the event loop.

Product/Culture Discussion

Engagement with engineering leadership or founders about product and cultural fit.

What to demonstrate

• Engagement with engineering leadership or founders about product and cultural fit
• Depth in SQL

How to prepare

• Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
• Re-read the description of the product/culture discussion above and write down what you would ask to confirm before it.

Where candidates lose points

Prioritize Code Simplicity in System Design

In system design interviews, candidates are often evaluated on their ability to build practical solutions rather than complex distributed setups. Start with simple, clean designs that address the core problem effectively before adding additional layers.

Practice Asynchronous Patterns in Python and TypeScript

Ensure you are comfortable with non-blocking concurrency, asynchronous state management, and handling dynamic event streams in your primary language.

Prepare Specific Product Motivation

Be ready to clearly articulate why you want to work at ElevenLabs. Demonstrating familiarity with their SDKs, voice models, and API ecosystem shows genuine interest and initiative.

During live practical coding sessions, treat the interviewer like a pair-programming partner

Clearly talk through your architectural assumptions, pseudocode approach, and dynamic state decisions before writing code.

Questions & practice

Simulate a multi-step grid event system where directional wind shifts affect the physical state and placement

Medium · Algorithmic Coding & Logic Puzzles

Simulate a multi-step grid event system where directional wind shifts affect the physical state and placement of leaves on an $N \times M$ matrix, returning the total remaining leaves after all wind events execute.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Solve a multi-pattern string array problem combining sliding window tracking with frequency maps under strict

Medium · Algorithmic Coding & Logic Puzzles

Solve a multi-pattern string array problem combining sliding window tracking with frequency maps under strict time complexity constraints.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Implement a hierarchical permission tree evaluation engine that resolves access control rules across dynamic p

Medium · Algorithmic Coding & Logic Puzzles

Implement a hierarchical permission tree evaluation engine that resolves access control rules across dynamic parent and child organizational nodes.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Given an unsorted stream of integer elements, merge sorted lists while removing duplicates in optimal time and

Medium · Algorithmic Coding & Logic Puzzles

Given an unsorted stream of integer elements, merge sorted lists while removing duplicates in optimal time and minimal auxiliary space.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Write an asynchronous database processing engine in Python or TypeScript that batches inbound streaming read/w

Medium · Asynchronous Systems & Real-Time Enginee

Write an asynchronous database processing engine in Python or TypeScript that batches inbound streaming read/write requests without blocking the event loop.

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

How do you manage concurrent async tasks when external third-party API dependencies introduce unpredictable re

Medium · Asynchronous Systems & Real-Time Enginee

How do you manage concurrent async tasks when external third-party API dependencies introduce unpredictable response latencies?

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Describe a situation where you had to make a high-stakes engineering decision with ambiguous requirements and

Medium · Behavioral & Product Ownership

Describe a situation where you had to make a high-stakes engineering decision with ambiguous requirements and tight deadlines.

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Implement a sequence tracking algorithm where every number is generated by adding the sum of its digits to its

Medium · Algorithmic Coding & Logic Puzzles

Implement a sequence tracking algorithm where every number is generated by adding the sum of its digits to itself. Write a method to calculate the exact join point where two sequences starting from different numbers intersect.

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. Handle the rows that do not match: that is usually the actual question.

Follow-up

• How does the query change if that join becomes one-to-many?
• What happens to this when the table is ten times larger?

Explain why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id =$2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

1. Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
2. For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
3. Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
4. Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

• 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
• A dashboard runs this for 40 owners in one page load. What changes about the design?

Implement an event-driven status propagation engine that tracks dubbing line updates across nested audio files

Medium · Asynchronous Systems & Real-Time Enginee

Implement an event-driven status propagation engine that tracks dubbing line updates across nested audio files and marks dependent sequences for re-review.

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Design a dynamic real-time data streaming pipeline capable of delivering chunked binary voice payloads over We

Medium · Asynchronous Systems & Real-Time Enginee

Design a dynamic real-time data streaming pipeline capable of delivering chunked binary voice payloads over WebSockets with minimal jitter and backpressure controls.

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Describe how you would handle connection drops and state recovery during an active real-time bidirectional aud

Medium · Asynchronous Systems & Real-Time Enginee

Describe how you would handle connection drops and state recovery during an active real-time bidirectional audio session.

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Design a live voice chat and conversational voice search architecture for an enterprise retail product catalog

Medium · System & Product Design

Design a live voice chat and conversational voice search architecture for an enterprise retail product catalog.

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Redesign a legacy spreadsheet-based dubbing workflow into a real-time collaborative system for voice actors an

Medium · System & Product Design

Redesign a legacy spreadsheet-based dubbing workflow into a real-time collaborative system for voice actors and sound editors.

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Architect an API rate limiter and quota management service designed to enforce per-second request constraints

Medium · System & Product Design

Architect an API rate limiter and quota management service designed to enforce per-second request constraints across global edge locations.

Approach

1. Say who the caller is and what they do when the call fails halfway.
2. Define the identity of a request so a retry cannot double-apply it.
3. Separate accepted, pending, failed and confirmed; they are different facts.
4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

• What happens if the caller retries after a timeout?
• How does a client discover it is on an old version of this contract?

How would you structure a distributed media processing queue to convert high-volume long-form audio files with

Medium · System & Product Design

How would you structure a distributed media processing queue to convert high-volume long-form audio files without encountering out-of-memory bottlenecks?

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Design a scalable permissions and tenant isolation system for enterprise accounts managing thousands of custom

Medium · System & Product Design

Design a scalable permissions and tenant isolation system for enterprise accounts managing thousands of custom AI voice clones.

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Every query on one table stalls for forty seconds mid-deploy

Medium · lock contention · ddl · migrations

During a release on PostgreSQL, every query touching resource times out for about 40 seconds and then recovers with no intervention. The release ran one migration, ALTER TABLE resource ADD COLUMN archived_reason TEXT, and the migration log shows it completing in 6 ms. Unrelated tables showed no change in error rate. Explain how a 6 ms statement caused a 40-second stall, give the ordered checks you would run on a live system to confirm it, and give the migration procedure that prevents a repeat.

Approach

1. Separate the statement's duration from the lock's duration. ADD COLUMN with no default is a catalogue-only change and genuinely runs in milliseconds, but it requires ACCESS EXCLUSIVE, and it cannot acquire that until every transaction already touching the table has finished.
2. Account for the queueing, which is the part that surprises people. A lock request that is waiting blocks later requests for conflicting modes behind it rather than letting them overtake, so one long-open transaction holds the DDL and the DDL holds all the traffic. The stall length is set by the longest open transaction, not by the size of the change.
3. Confirm on a live system in this order: pg_stat_activity for that table ordered by xact_start, looking for the oldest transaction and specifically for state = idle in transaction; then pg_locks where granted = false to find the waiter; then join them on pid to name blocker and blocked. pg_blocking_pids() does that join for you and is the fastest single call.
4. Prevent rather than merely time it better. Set lock_timeout to a second or two on the migration session so the DDL abandons the queue after a bounded wait and is retried, instead of holding it for as long as the oldest transaction lives. Be exact about what that buys: queries arriving during the wait still queue behind the pending ACCESS EXCLUSIVE request, so each attempt costs them up to one lock_timeout of added latency. The outage goes from 40 seconds to about one second per attempt, not to zero. Also run migrations away from deploy-time peaks, and put a statement timeout and an idle-in-transaction timeout on the analytics role that opens the long transactions.

Follow-up

• The same release also wants NOT NULL on that column. What is the sequence that gets there without a long lock?
• Your lock_timeout retry fails ten times in a row because the analytics transaction is always open. What do you change?

Suggested practice checklist

Built from the rounds and topics ElevenLabs candidates report.

Day 1 — Map the ElevenLabs loop

• Write out the reported sequence: Online Screening, Recruiter Conversation, Technical Rounds, Product/Culture Discussion.
• For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 4 reported rounds, with the weakest marked.

Day 2 — Work SQL

• Spend the session on SQL, which ElevenLabs candidates report being tested on.
• Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 3 — Work React

• Spend the session on React, which ElevenLabs candidates report being tested on.
• Write one worked example in React and time yourself on it.

Deliverable: One timed worked example in React.

Day 4 — Work Live coding (interactive implementation)

• Spend the session on Live coding (interactive implementation), which ElevenLabs candidates report being tested on.
• Write one worked example in Live coding (interactive implementation) and time yourself on it.

Deliverable: One timed worked example in Live coding (interactive implementation).

Day 5 — Answer out loud: Algorithmic Coding & Logic Puzzles

• Answer aloud, timed: Implement a sequence tracking algorithm where every number is generated by adding the sum of its digits to itself. Write a method to calculate the exact join point where two sequences starting from different numbers intersect.
• Answer aloud, timed: Simulate a multi-step grid event system where directional wind shifts affect the physical state and placement of leaves on an $N \times M$ matrix, returning the total remaining leaves after all wind events execute.

Deliverable: Spoken answers to 2 reported Algorithmic Coding & Logic Puzzles question(s), under time.

Day 6 — Answer out loud: Asynchronous Systems & Real-Time Engineering

• Answer aloud, timed: Write an asynchronous database processing engine in Python or TypeScript that batches inbound streaming read/write requests without blocking the event loop.
• Answer aloud, timed: Implement an event-driven status propagation engine that tracks dubbing line updates across nested audio files and marks dependent sequences for re-review.

Deliverable: Spoken answers to 2 reported Asynchronous Systems & Real-Time Engineering question(s), under time.

Day 7 — Answer out loud: System & Product Design

• Answer aloud, timed: Design a live voice chat and conversational voice search architecture for an enterprise retail product catalog.
• Answer aloud, timed: Redesign a legacy spreadsheet-based dubbing workflow into a real-time collaborative system for voice actors and sound editors.

Deliverable: Spoken answers to 2 reported System & Product Design question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Why ElevenLabs? What specific technical or product domain here excites you most?

Medium · Behavioral & Product Ownership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Walk me through a complex technical feature you owned end-to-end that you are particularly proud of. What trad

Medium · Behavioral & Product Ownership

Walk me through a complex technical feature you owned end-to-end that you are particularly proud of. What trade-offs did you make?

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

How do you balance writing pristine, fully tested code against the need to ship features rapidly in a fast-pac

Medium · Behavioral & Product Ownership

How do you balance writing pristine, fully tested code against the need to ship features rapidly in a fast-paced environment?

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Tell me about a time you collaborated directly with non-technical stakeholders to turn a complex user workflow

Medium · Behavioral & Product Ownership

Tell me about a time you collaborated directly with non-technical stakeholders to turn a complex user workflow into a functional product interface.

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?