Red Belt · Promotion exam · LAD

LLM API Developer

Validates that you can implement application features with LLM APIs and manage quality, cost and latency using structured output, tool calling, streaming and caching.

Daily practice · Free

10 questions · 20 min · No sign-up needed

Mock exam · Fair-exam rules

30 questions · 50 min · Free · In the app

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Promotion exam · Proctored

30 questions · 50 min · Raw score of 70 or more · $3.99 / one attempt

Promotion exam details

Exam overview

Questions
30
Time
50 min
Pass mark
70 pts
Recommended experience
At least 1 year of experience developing HTTP APIs

Every question has five choices and is marked on an OMR answer sheet. Multiple-choice and true-or-false questions ask for the right combination from a box; ordering and matching questions ask for the right arrangement. Judgment questions (L3) are worth 3 points and all others 2; the raw score is converted to a 100-point scale and graded 1 to 9.

Exam domains

  1. 1. API basics and message design20%

  2. 2. Structured output and tool calling25%

  3. 3. Performance and cost optimization20%

  4. 4. Reliability and error handling20%

  5. 5. Evaluation and operations15%

Weights follow the Promotion exam. Practice and mock exams may mix domains differently.

What this exam verifies

  • Get the intended response reliably through message structure and parameters
  • Connect models to the application with structured output and tool calling
  • Reduce latency and cost with streaming, batching and caching
  • Handle errors, rate limits and retries robustly
  • Maintain quality through evaluation and monitoring

Who it is for

  • Backend and full-stack developers adding LLM features to products
  • Engineers moving AI feature PoCs into production

Does not cover model pre-training or operating GPU infrastructure.

Domain details

Domain 1. API basics and message design

  • Knowledge: Message roles, Tokens and maximum output, Sampling parameters such as temperature, Model selection
  • Skills: Choose the model and parameters that fit the requirements

Domain 2. Structured output and tool calling

  • Knowledge: Structured output based on JSON Schema, Tool definitions, The tool-calling loop, Parallel tool calls
  • Skills: Validate output against the schema, Return tool results to the conversation

Domain 3. Performance and cost optimization

  • Knowledge: Streaming, Prompt caching, Batch API, Routing by model tier
  • Skills: Arrange prompts to raise the cache hit rate, Weigh latency against cost

Domain 4. Reliability and error handling

  • Knowledge: Rate limits, Exponential backoff, Timeouts, Idempotency, Interrupted responses
  • Skills: Tell retryable errors apart from the rest, Recover from partial failures

Domain 5. Evaluation and operations

  • Knowledge: Evaluation sets, Logging and tracing, Handling personal information, Pinning model versions
  • Skills: Run regression evaluations before switching models, Define operational metrics

Official documentation

OpenAI

Anthropic

Google

Red Belt Course · LLM API Developer

Practice, mock exams and every course book are free. Pay only when you take an official test.