Heidelberg Catechism

What Heidelberg Catechism is

The Heidelberg Catechism app is a standalone mobile reader and study tool for the 1563 catechism of the same name. The app contains the full English text of the 129 questions and answers, divided into the traditional 52 Lord’s Days, with the scripture references that have accompanied the catechism since its original publication. It is available on iOS and Android, runs offline after install, and asks nothing of the user — no account, no subscription, no analytics opt-in dance.

Functionally it does three things. It lets you read the catechism in its native weekly structure. It lets you look up any individual question or proof-text. And it lets you memorize the answers using a simple hide-and-reveal drill. That is the entire surface area, and it is the right surface area for this confession.

Why Reformed readers prefer a single-confession app

The Heidelberg Catechism is unusual among Reformation documents in that it was written to be used in a specific way: one Lord’s Day per week, fifty-two weeks per year, preached or taught alongside Sunday worship. That rhythm is the whole architecture of the document, and most general Bible apps flatten it. They will give you the text as a single long document, or buried inside a larger confessions module, with no sense that the original authors expected you to live with it across a calendar year.

A single-purpose app respects the work. The Lord’s Day index is the default screen. The week’s questions are grouped the way Ursinus and Olevianus grouped them. The proof-texts sit under the answer they were chosen for, not in a separate cross-reference pane. None of this is revolutionary — it is just the catechism behaving like the catechism, which is exactly what people who care about it want from a phone app.

Lord’s Day structure: the catechism the way it was meant to be used

The app’s primary navigation is the 52 Lord’s Days, not the 129 questions. Open the app and you see a list of weeks; tap a week and you see the two to seven questions assigned to it, grouped under the historical headings the catechism uses (Misery, Deliverance, Gratitude — the three-part scheme of Lord’s Days 2-4, 5-31, and 32-52). You can jump straight to question 1, of course, but the default view is the calendar view, and that is the right default.

This sounds like a small thing. In practice it is the difference between reading the catechism and using the catechism. Congregations that preach through Heidelberg in a year, families that read a Lord’s Day after Sunday dinner, and classes that work week-by-week through confirmation — all of them inherit a built-in pace from the document itself, and the app keeps that pace visible. You always know where you are in the cycle, and you always know what week is next.

Memorization mode: the simplest flashcard loop that works

The memorization mode is exactly what you would expect and nothing more. You see a question. You think (or say aloud) the answer. You tap to reveal the official text. You move to the next question. You can drill within a single Lord’s Day, across a range, or across the full 129. There is no streak counter, no XP, no gamification — just the questions and your own honesty about whether you got the answer.

For Q1 and a handful of others this is the killer feature. The Heidelberg answers are often paragraph-length, written in the first person, and meant to be internalized rather than merely understood. "That I am not my own, but belong with body and soul, both in life and in death, to my faithful Saviour Jesus Christ" — the kind of sentence that does its work when it is in your bones, not just in your bookmarks. A clean Q→A drill on a phone is the model that respects that work. The catch — noted in the cons — is that there is no spaced-repetition scheduling, so long-term retention is on you.

Scripture proof-texts: the references in their original home

Every answer in the catechism is accompanied by scripture references — sometimes a single verse, often a cluster of three or four. These were chosen by the catechism’s authors (with later additions in the Reformed tradition) to ground each answer in the biblical text rather than in the authority of the catechism itself. The app surfaces these proof-texts beneath each answer, with the reference visible and (depending on the build) tappable to expand the verse.

For confessional Reformed readers this is the point. The catechism is not a freestanding system; it is a structured exposition of what the authors believed scripture teaches, and stripping the proof-texts strips the document of half its argument. The app keeps the proofs attached. The execution is plain — references rather than a full embedded Bible — but it is the right plainness for an app this small, and most users already have a Bible app open in the next tab anyway.

Pricing

Where Heidelberg Catechism falls behind

No spaced-repetition memorization. The drill is manual. You decide what to review and when, and there is no algorithm tracking which answers you keep blanking on. For deep memorization across all 129 questions, a dedicated SRS app (Anki, Scripture Typer, RemNote) with the catechism content loaded in will retain the material longer — at the cost of significant setup.

No audio. The catechism rewards being heard. Reading Q1 aloud, hearing it read back, listening on a commute — all of that is well within the reach of a 2026 app, and it is conspicuously missing here. A few third-party audio recordings of the Heidelberg exist on YouTube and on Reformed church sites, but nothing is integrated.

No second confession. If you are confessionally Reformed and also reach for the Belgic Confession or the Canons of Dort — the other two Forms of Unity — you will need a separate app or a website. The same is true for Westminster Standards users who want to keep their tradition’s documents alongside Heidelberg in one place.

No notes or highlights. You cannot mark up the text, write a comment on an answer, or save a passage to a notebook. For the average reader this is fine; for a pastor preparing a Heidelberg sermon series or a student working through a confessions course, it pushes you back to a paper copy or to Logos.

No web companion or cross-device sync. The app lives on your phone, full stop. Open it on a different device and you start over. This is not a dealbreaker for a 129-question document, but it is a real limitation for anyone used to syncing study work across phone, tablet, and desktop.

Heidelberg Catechism vs. New City Catechism vs. Westminster Shorter Catechism

These three are the catechisms most likely to live on a Reformed or Reformed-adjacent reader’s phone, and they serve genuinely different purposes. Different strengths.

The Heidelberg Catechism app is the most traditional of the three: a sixteenth-century confessional document presented in its native Lord’s Day structure, used as a doctrinal standard by continental and Dutch Reformed churches and many of their American descendants. It is the right tool if you are working through Heidelberg specifically — whether because your congregation preaches it, your family reads it, or your tradition confesses it.

The New City Catechism (a free Gospel Coalition / Redeemer project, available as an app and as a website) is the modern entry: 52 questions written in 2017, drawing on Heidelberg, Westminster, and Calvin’s Geneva Catechism, with built-in commentary, video, and music for memorization. It is broader-church evangelical-Reformed in tone, designed for families and small groups who want a catechism but do not want to take on the full weight of a confessional standard. Lighter, more polished, more pastoral framing.

The Westminster Shorter Catechism is the Presbyterian standard — 107 questions, more compact and propositional than Heidelberg, the doctrinal heritage of PCA, OPC, ARP, Free Church, and many other Presbyterian bodies. Several free apps exist for it (Reformed Forum and others have published versions), with similar memorization and proof-text features to the Heidelberg app. If your tradition confesses Westminster, that is the app you want, not this one.

Heidelberg is warmer and longer-form. New City is shorter and modernized. Westminster is tighter and more systematic. Pick the catechism your tradition actually uses, and the app choice follows.

Alternatives to Heidelberg Catechism