Deco planner comparison

Abysner vs Dive Kit

Two honest Bühlmann planners, built around different priorities

Both run the Bühlmann ZH-L16 model with gradient factors, fully offline on iOS and Android, and both plan open circuit and CCR. Abysner is open-source and a few dollars on the app stores (free if you build it yourself), with an engine you can read. Dive Kit is a pricier deco planner wrapped in a free toolkit, with more sophisticated CCR and contingency tooling, plan sharing, and six languages. Neither is a cut-down version of the other.

Abysner

Dive Kit

Common ground

The same engine family where it counts

Both planners are built on the model most technical divers already trust.

Bühlmann ZH-L16 with gradient factors

Sixteen tissue compartments, with nitrogen and helium tracked separately so trimix is handled correctly. Abysner lets you pick the A, B, or C coefficient set; Dive Kit uses C.

Open and closed circuit, offline

Both plan open-circuit and CCR dives entirely on-device, with no network connection needed, on iOS and Android.

Oxygen, environment, repetitive dives

Both accumulate CNS and OTU, account for altitude and water salinity, and carry tissue state across a surface interval for repetitive dives.

Two correct ZH-L16C implementations can still produce slightly different schedules, because the model leaves last-stop handling, stop rounding, and gas-switch timing to the implementer. That is why both projects encourage cross-checking. Abysner earns trust by letting you read its Kotlin engine. Dive Kit's engine is closed, so it earns trust the other way: by publishing a reproducible cross-reference against MultiDeco across 26 scenarios.

See the engine write-up & the full MultiDeco comparison

How they feel to use

Where the two planners overlap, and where each one goes further.

One screen, no clutter

Abysner puts cylinders, the dive profile, and the deco plan on a single scrolling screen, and it is genuinely pleasant to move around. Dive Kit splits the same inputs into labelled cards with live END, gas density, and ppO₂ feedback as you type.

Abysner

Dive Kit

Choosing a gas

Both make gas selection quick and show MOD and density at a glance. Both cap ppO₂, differently: Abysner uses two global limits (1.4 working, 1.6 deco), while Dive Kit caps per gas and bands deco-gas switching by the gas's O₂ content (lean 1.4 / mid 1.5 / rich 1.6), so the same cap drives the switch depth and the hyperoxia warning.

Abysner

Dive Kit

The deco plan

Both produce a clean stop table with a depth-and-ceiling profile, CNS and OTU, and deeper-or-longer contingency views. Dive Kit can show stop times rounded to whole minutes, to 30 seconds, or exact.

Abysner

Dive Kit

Gas planning

Abysner's gas plan is a real strength: it works cylinder pressures from real-gas behavior rather than the ideal gas law, and shows used, reserve, and remaining per cylinder with density and ppO₂ limits. Dive Kit shows per-cylinder consumption bars across the whole dive, contingencies included.

Abysner

Dive Kit

Sharing a plan

Abysner renders a clean plan image you can save and send. Dive Kit also shares a plan as a QR code or URL that opens straight into a buddy's app with every scenario and warning intact, or in a browser-based web viewer if they do not have the app. Its slate export is a high-contrast black-and-white slate at A6 size, output as an image or a PDF, so it scales cleanly onto a real wrist slate or a printed card.

Abysner

Dive Kit

A planner, or a whole kit

Abysner keeps the tools a plan needs inside the planner and stays focused, which is a fair design choice. Dive Kit surrounds the planner with a dozen free standalone tools, Gas Blender (partial-pressure and continuous/rotameter), Best Mix, a Gas Analyzer for EAD/END/ppO₂, Gas Usage, RMV/SAC, a neoprene-aware Buoyancy & weighting calculator, Unit Converter, and a cylinder database, plus a dive log, gear and weighting tracking, and certification cards. It is a dive companion, not just a planner.

Dive Kit only

Feature by feature

Where Abysner and Dive Kit are the same, and where they part ways.

Feature	Dive Kit	Abysner	Notes
Algorithm	ZH-L16C	ZH-L16 A/B/C	Both are Bühlmann with gradient factors. Abysner lets you choose the coefficient set.
Gradient factors	Yes	Yes	GF Low and GF High, interpolated with depth, in both.
Open circuit	Yes	Yes	Multi-gas with MOD-based switching in both.
CCR	Yes	Yes	Both plan CCR with descent and bottom setpoints, an auto-switch depth, loop volume and metabolic O₂. Dive Kit goes further: a depth-keyed deco-setpoint schedule, dilout switches, air breaks, and an OC bailout view with an isobaric counter-diffusion check.
Trimix / helium	Yes	Yes	Nitrogen and helium tracked separately in both.
ppO₂ model	Per-gas, O₂-banded	Working / deco caps	Abysner uses two global limits, max ppO₂ 1.4 in the working phase, 1.6 in deco. Dive Kit caps ppO₂ per gas and bands deco-gas switching by O₂ content (lean 1.4 / mid 1.5 / rich 1.6).
Stop-time precision	Whole · 30s · exact	Whole minute	Dive Kit can show whole-minute, 30-second, or exact stop times; Abysner rounds to whole minutes.
Contingency planning	Yes	Partial	Dive Kit has presets plus a custom builder (lost gas, depth/time deltas); Abysner generates a deeper-and-longer plan.
Plan variants	Yes	Partial	Dive Kit saves named variants with graph overlay; Abysner offers deeper / longer views.
Safety warnings	Yes	Partial	Dive Kit has a severity-sorted warning sheet recomputed per scenario; Abysner surfaces CNS, OTU, ppO₂, and density warnings.
Altitude & salinity	Yes	Yes	Both fold altitude and water type into ambient pressure and the ceiling.
Repetitive dives	Yes	Yes	Tissue carry-over across a surface interval in both.
CNS / OTU	Yes	Yes	Both accumulate oxygen exposure.
Plan sharing	QR · URL · web · slate	Plan image	Both export a plan image; Dive Kit adds QR and URL deep links and a web viewer.
Companion tools	11+	In-planner	Dive Kit ships standalone calculators, logging, gear, and certs; Abysner keeps supporting tools inside the planner.
Languages	6 languages	English
Open source	No	Yes	Abysner is AGPL-3.0, so its deco engine is fully auditable. Dive Kit's engine is closed-source.
Stated validation	vs MultiDeco (published)	Open source + author checks	Dive Kit publishes a 26-scenario cross-reference against MultiDeco; Abysner's validation is its readable source and the author's own cross-checks.
Price	$24.99 lifetime	$2.99	Abysner is $2.99 on the App Store (or free to build from source). Dive Kit's deco planner is $24.99 lifetime; its companion tools are free.
Platforms	iOS · Android	iOS · Android	iOS and Android in both.
Works offline	Yes	Yes	Both calculate entirely on-device.
Maturity	Shipping	Beta (2.1.1)	Abysner labels itself beta and recommends cross-checking its output.
Units	Metric · Imperial	Metric · Imperial	Both support metric and imperial (Abysner added imperial in 2.1.0).

Only Dive Kit does this

Full CCR loop: a depth-keyed deco-setpoint schedule, dilout switches, and air breaks
A custom contingency builder (lost gas plus depth/time deltas)
Plan sharing by QR, URL deep-link, web viewer, and an A6 printable slate (image or PDF)
Sub-minute stop-time precision (whole-minute, 30-second, or exact)
An O₂-banded deco ppO₂ model (lean 1.4 / mid 1.5 / rich 1.6)
A free toolkit: Gas Blender (partial-pressure + continuous), Best Mix, Buoyancy & weighting, Gas Analyzer, SAC/RMV, and more
A dive log, gear & weighting tracking, and certification cards
In-app tutorials and a public guide site for divers still learning
Six languages (English, German, Polish, Russian, Swedish, Turkish)

Frequently asked questions

Abysner vs Dive Kit, answered honestly.

Is Abysner free?

Not on the app stores, but it is inexpensive: $2.99 on the App Store, cheaper than most planners. Because it is open-source under AGPL-3.0, you can also build it yourself for free. Dive Kit's deco planner is $24.99 lifetime.

Do Abysner and Dive Kit use the same decompression algorithm?

Both use the Bühlmann ZH-L16 model with gradient factors over 16 compartments. Abysner lets you choose the A, B, or C coefficient set; Dive Kit uses C. Set the same variant and gradient factors and the two agree closely on the model itself.

Is Abysner open-source, and can I read its deco engine?

Yes. The algorithm lives in Buhlmann.kt in the public repository under AGPL-3.0, so anyone can audit it. Dive Kit's engine is closed-source and is instead cross-checked against MultiDeco, with the reference data published.

Does Abysner support imperial units?

Yes, since version 2.1.0-beta, with metric and imperial available. The README text still says metric only, but the release notes and the app itself support imperial.

Does Abysner support CCR or rebreather diving?

Yes. Abysner plans CCR with a descent and bottom setpoint, an auto-switch depth, loop volume and metabolic O₂. Dive Kit's CCR is more sophisticated: a depth-keyed deco-setpoint schedule, dilout switches, air breaks, and an OC bailout view with an isobaric counter-diffusion check.

Which is better for technical or CCR diving?

Both handle trimix and CCR. Dive Kit offers more CCR control (a multi-step deco-setpoint schedule, dilout switches, air breaks) and a custom contingency builder; Abysner offers an open, auditable engine and a choice of ZH-L16 variant. For open-circuit tech, both are capable.

Is Abysner production-ready?

It is in active beta (2.1.1), and the author recommends cross-checking its output against other tools. Treat it as capable but still maturing.

What languages does each app support?

Abysner is English only. Dive Kit ships six languages: English, German, Polish, Russian, Swedish, and Turkish.

How accurate is Dive Kit if the engine is closed-source?

Dive Kit's engine is cross-checked against MultiDeco across 26 scenarios spanning open circuit, CCR, trimix, altitude, and lost-gas cases, with the reference data published. We have not run a numeric schedule comparison against Abysner; this page compares features and implementation, not measured deco tables.

Can I cross-check plans between Abysner and Dive Kit?

Yes, and it is a good habit. Set the same algorithm variant, gradient factors, gases, and last-stop depth in both. Small schedule differences are normal between any two correct ZH-L16C tools.

Sources

Abysner details were verified from its open-source repository (AGPL-3.0, github.com/NeoTech-Software/Abysner) and its store listings, version 2.1.1, on 2026-06-03. We have not run a numeric schedule comparison between the two engines, so this page compares implementation and features, not measured deco tables.

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