20+ Best Alternatives to Castelion in 2026
Mass-producing affordable hypersonic weapons for defense
Looking for an alternative to Castelion? Below are 20 AI startups working in the same space — ranked by our Neuron score so the most credible options come first. Each card shows what makes the tool a viable substitute, pricing signals, and funding stage.
- 1View alternative →
Skydweller Aero
$45MSolar-powered autonomous aircraft for perpetual flight
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 2View alternative →
Anduril Drones
$7.5BAutonomous defense drones and counter-UAS systems.
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 3View alternative →
Skyryse
$600MAI-powered fly-by-wire system for any aircraft
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 4View alternative →
Shield AI
$2.0BAutonomous AI software for defence
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 5View alternative →
Astranis
$1.2BThe world's only dedicated satellite networks providing flexible, resilient, high-speed communications for global customers.
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 6View alternative →
Mach Industries
UndisclosedBuilding next-generation defense platforms to maintain an allied American edge and deter kinetic conflict.
Why it's similar: Shares categories with Castelion — Defense AI, AI Aerospace.
💵 Enterprise · Contact sales
- 7View alternative →
Epirus
$550MHigh-power microwave systems that disable drone swarms in flight
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 8View alternative →
Vannevar Labs
$90MAI-powered intelligence and electronic warfare software for national security
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Free
- 9View alternative →
Auterion
$180MSoftware-defined autonomy and AI for drone swarms across air, land and sea
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 10View alternative →
Apex Space
$718MProductized satellite buses manufactured at scale
Why it's similar: Shares categories with Castelion — AI Aerospace.
💵 Free
- 11View alternative →
HavocAI
$96MCollaborative maritime autonomy for fleets of uncrewed surface vessels
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 12View alternative →
Overland AI
$142MOff-road ground autonomy for military vehicles in GPS-denied terrain
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 13View alternative →
Second Front Systems
$152.1MGame Warden delivers software to classified government environments fast
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 14View alternative →
Portal Space Systems
$67.5MRapidly maneuverable spacecraft powered by solar-thermal propulsion
Why it's similar: Shares categories with Castelion — AI Aerospace.
💵 Free
- 15View alternative →
Xoople
$225MBuilding Earth's system of record for the agentic AI era
Why it's similar: Shares categories with Castelion — AI Aerospace.
💵 Enterprise · Contact sales
- 16View alternative →
CX2
$46MAI-enabled electronic warfare across the electromagnetic spectrum
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Free
- 17View alternative →
Turion Space
$100MSpace domain awareness and on-orbit imaging for space superiority
Why it's similar: Shares categories with Castelion — AI Aerospace.
💵 Free
- 18View alternative →
Blue Water Autonomy
$64MBuilding the world's most capable fully autonomous warships
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
- 19View alternative →
Firehawk Aerospace
$88M3D-printed rocket propellant and solid rocket motors for defense
Why it's similar: Shares categories with Castelion — AI Aerospace.
💵 Free
- 20View alternative →
Digantara
$64.5MSpace-based surveillance and missile tracking from infrared sensors
Why it's similar: Shares categories with Castelion — Defense AI.
💵 Enterprise · Contact sales
Frequently asked questions
What are the best alternatives to Castelion?
The top-ranked alternatives to Castelion on NeuronFeed are Skydweller Aero, Anduril Drones, Skyryse, Shield AI, Astranis. Rankings are based on our Neuron score, which weighs funding, momentum and editorial signal.
Is there a free alternative to Castelion?
Yes — Vannevar Labs, Apex Space, Portal Space Systems offer a free plans. See the pricing column for each alternative above.
How is this list ranked?
We rank alternatives by shared categories with Castelion, then by our proprietary Neuron score (0–100) which combines funding, team quality, momentum, and editorial input. The list refreshes every 30 days.
Castelion vs Skydweller Aero — which is better?
It depends on use case. Skydweller Aero (Solar-powered autonomous aircraft for perpetual flight) is the #1-ranked alternative. See the full side-by-side at /compare/castelion-vs-skydweller-aero.
Explore more around Castelion
Contextual paths to related AI startups, deals and rankings.