Building Systems with the ChatGPT API vs ChatGPT Prompt Engineering for Developers

Across 11 short lessons (roughly 90 minutes total), the course covers a complete pipeline for multi-step LLM systems: how language models and tokenisation work, the chat format and system-user message separation, input classification for query routing, the OpenAI Moderation API, chain-of-thought prompting to handle multi-step questions, chaining several focused prompts where each consumes the previous output, output checking, and a two-part section on evaluating LLM responses at the system level. Reviewers consistently praise the logical progression and the theory-to-practice balance. The principal mark-down is age and depth: the course was built on GPT-3.5 Turbo in 2023 and has not been meaningfully updated, so it predates tool calling, structured JSON outputs, and reasoning models, and it stops short of real-world deployment concerns such as latency management, cost at scale, and production observability.

Isa Fulford, Member of Technical Staff at OpenAI, leads the code demonstrations while Andrew Ng frames the broader concepts and asks the questions a beginner would actually ask. Reviewers across blogs and Coursera call the pairing "highly knowledgeable and effective communicators." The teacher-demonstrator dynamic mirrors how a learner thinks through a new problem step by step, keeping each lesson of five to twenty minutes focused and coherent. Because Fulford comes directly from the team that built the ChatGPT API, the design decisions behind the Moderation API, the chat format, and tokenisation carry genuine authority rather than third-hand explanation.

The course is free on the DeepLearning.AI platform with every Jupyter notebook runnable directly in-browser — no OpenAI API key, no local Python environment, and no subscription required. The Coursera guided-project version is also free to audit. For roughly 90 minutes of hands-on instruction from two of the most credible names in the field, delivering reusable architecture patterns for multi-step LLM systems, the value proposition is essentially unmatched among paid or free alternatives. The only caveats are that a graded assignment and certificate on the Coursera version sit behind a paid enrolment, and the free tier leaves no portfolio artefact by default.

The patterns taught — classify the input, moderate for safety, reason in steps, chain focused prompts rather than one monolithic prompt, then evaluate the output — are exactly how production LLM features are structured in practice. Multiple reviewers note that the progression from basic API calls to a multi-stage orchestrated system reflects real engineering work. The gap is that the 2023 course predates the patterns now central to production LLM development (tool calling, structured outputs, retrieval-augmented generation), and at least one practitioner reviewer noted that the finished chatbot example would require substantial hardening before it approached something ready for deployment beyond a prototype.

Every lesson pairs a video with a runnable Jupyter notebook, and the course builds one coherent end-to-end example: a customer-service chatbot that classifies incoming queries, runs them through the Moderation API, applies chain-of-thought prompting to multi-step reasoning, chains successive focused prompts, retrieves product information, and evaluates whether its own output actually addresses the user's question. The Coursera version holds a 4.7/5 rating across 346 learners. The caveat is that there is no graded project or kept portfolio artefact on the free tier, and the supplied notebooks now require fixes (deprecated API syntax, missing helper files) to run locally outside the course sandbox.

Two core principles (write clear and specific instructions, give the model time to think) plus modules on iterative prompt development, summarizing, inferring, transforming, expanding, and building a chatbot. Reviewers praise the clarity and the runnable Jupyter notebooks. The honest limit is depth: it was built in April 2023 on GPT-3.5 Turbo and does not cover newer patterns like tool calling, structured outputs, or reasoning models.

Isa Fulford (OpenAI) and Andrew Ng (DeepLearning.AI) are about as authoritative as the field gets. The teacher-student dynamic — Ng asking the clarifying questions a beginner would ask while Fulford demonstrates — is repeatedly cited as a strength that mirrors how learners actually think.

Free on the DeepLearning.AI platform with every code example runnable in-browser, no API key or local setup required. Reviewers consistently call out "the best part is that it's free" as a decisive advantage over the paid prompt-engineering courses that flooded the market in 2023.

Being a one-hour self-paced short course, there is no graded assignment, cohort, or mentor support. The OpenAI and DeepLearning.AI community forums are active and useful, but learners are largely on their own. For a course this short the need is limited, but there is no structured help.

Six practical use cases implemented end-to-end give learners patterns they can apply the same day. Developers report it directly improved their ability to build LLM features. The caveat is that the API-level patterns are a foundation, not a production blueprint — several reviewers wanted more on structuring LLMs into real applications.