If you already use ChatGPT to study, you have probably asked yourself: is ChatGPT enough, or do I need a tool built for oposiciones? The short answer is that they are different things and can be combined. The long answer, without adjectives and with the source of every figure, is this.
I write this comparison from Oposilab, so I owe you two things: to say clearly what ChatGPT does better, and not to invent a single figure. Price and limit data are in the dated comparison, which is generated with the real numbers from the database and cites the source of every external fact.
The underlying difference: where the answer comes from
Both use language models. The difference is what the model has in front of it when it answers.
- ChatGPT answers from its general model and, if enabled, from web search or the documents you paste. It is not limited to your syllabus. It can cite articles if asked, but the citation is not linked to a consolidated text inside the tool: checking it in the BOE is on you.
- Oposilab only answers from your exam's official syllabus, indexed article by article. Every statement carries the article citation and the citation opens the literal text of the rule without leaving the question. The corpus is checked every week against the BOE. It does not answer about user-uploaded PDFs.
That does not make Oposilab smarter. It makes it narrower, which is what you want when what you study has an official text.
What ChatGPT does better
- Understanding a concept on the fly. Pasting a paragraph of Law 39/2015 and asking for an explanation with an example works very well.
- Summarising and outlining. Summaries of a whole topic, tree outlines, comparisons between two legal figures.
- Exploring approaches to a practical case. Asking for five ways to frame a case helps you think, even if each one then has to be checked against the rule.
- Rehearsing an oral exam. It can play the board and hold an open conversation.
- Everything that is not your exam. Writing, translating, organising.
What Oposilab does better
- Ready-made topic tests, with explanation and citation on every question, plus AI-generated tests within the plan limits. You can try ten real questions without signing up in the Auxiliar Administrativo del Estado sample test.
- Mock exams with your call's structure: number of questions, reserve questions, time and penalty, verified against the published call and linked on each exam page.
- Spaced repetition (SM-2) fed by your mistakes. Every missed question comes back when it is due, with its explanation and its article.
- AI-marked practical cases, with the citation for each criterion.
- A tutor that cites. When it answers, you see the article and can read it in full.
What Oposilab does not do
- It does not cover every exam. The catalogue is on the exams page; if yours is not there, ChatGPT or any other tool will serve you better.
- It does not include official exams from previous calls: questions are generated from the text of the laws.
- It is useless for anything that is not your exam.
- It does not hold open conversations outside the syllabus: if you ask about something not in your programme, it will tell you.
Price
ChatGPT Plus cost €22.99 per month and ChatGPT Go €7.99 per month on the Spanish App Store according to Ranquia's guide updated on 14 August 2026; web price and VAT are confirmed at checkout. Oposilab has a Free plan with no card and the Pro plan costs €19 per month or €149 per year. The limits of each plan come from the database and are on the pricing page.
There is no single answer on which is cheaper: it depends on whether you already pay for ChatGPT for other reasons and on whether what you need is to understand or to practise.
How to combine them
A reasonable way to split your time, with no magic percentages:
- Study and practise on Oposilab: read the article, take the topic test, let the mistakes enter the review queue and take a weekly mock exam with the real penalty.
- Use ChatGPT when you do not understand something: ask for an example or an outline of the concept, then go back to the article to check that the example fits the text.
- Never memorise a citation you have not read. Not from ChatGPT and not from Oposilab: on Oposilab the citation opens with a click precisely for that.
If you want the full comparison with the data table and the sources, it is at Oposilab vs ChatGPT. And if you are interested in how to organise your preparation with AI in general, read the guide to preparing oposiciones with AI.
