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Head to head · Assistant proactive · October 2026 research run

Gemini Spark vs Leon

Leon scores 41 (E) on agent readiness against Gemini Spark's 24.5 (F), and leads in 5 of 7 scored categories. Gemini Spark leads on security & auth. Both do assistant proactive.

Best AI personal assistants that act for one person · All 190 assistants comparisons

Gemini SparkGoogle LLC · Platform F24.5/100#974 of 986 LeonLouis Grenard (Leon AI) · Agent harness E41/100#934 of 986

Which one, for what

Gemini Spark F

Best for A person who already keeps mail, calendar and files in a personal Google Account and accepts Keep Activity being on.

Ahead on

  • Security & auth, 60 against 34

Watch for

No public API, SDK or MCP server for an outside agent was found. Spark is reached in the Gemini mobile app, the Mac app and gemini.google.com

Leon E

Best for A developer who wants a self-hosted assistant with memory, computer use and a local model, and who will read the source.

Ahead on

  • Reliability, 32 against 14
  • Schema & documentation, 33 against 17
  • Agent ergonomics, 57 against 9
  • Payments & pricing, 60 against 10
  • Transparency & trust, 60 against 49

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • Open source

Watch for

No tagged release of the core since 1.0.0-beta.8 on 1 May 2023. The 2.0 Developer Preview is installed by cloning the develop branch

Score by category

CategoryWeight this runGemini SparkLeonEdge
Reliability16%201432Leon +18
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.21733Leon +16
Agent ergonomics13%16.2957Leon +48
Security & auth14%17.56034Gemini Spark +26
Payments & pricing10%12.51060Leon +50
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81715Gemini Spark +2
Transparency & trust7%8.84960Leon +11
Negative events≤1500
TotalF 24.5/100E 41/100

Facts side by side

FactGemini SparkLeon
KindPlatformAgent harness
VendorGoogle LLCLouis Grenard (Leon AI)
Hosted endpointno (local only)no (local only)
Transports
AuthOAuthNone
PricingPaidFree
x402nono
LicenceProprietary hosted service under the Google Terms of ServiceMIT
Read-only variant documentednono
llms.txtnono
Last release2026-05-192023-05-01
Terms last updated2026-07-30no document linked
Privacy policy last updated2026-09-24no document linked
Customer content may train modelsyes, with an opt-out
Terms restrict automated accessyes
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Popularitynone18k stars

Verdicts

Gemini Spark

Google's help pages state what Spark confirms before doing, how to delete its remote browser and code data, and the risks of prompt injection. Spark has no public API, Google calls it experimental, and it runs only with Keep Activity on, the setting under which chats are used for model training and human review.

Leon

Connected-app credentials are encrypted per profile and the Gmail connection is read-only. The 2.0 Developer Preview has no tagged release, runs tools and a 30-minute proactive pulse with no approval step, listens on every network interface with client authentication off, and sends telemetry by default.

Before you call either

Gemini Spark

  1. Do not plan an integration against Spark. No public API or MCP server was found, and a person must hold a Google AI Pro or Ultra subscription
  2. Expect a confirmation request before sends, edits, purchases and web form submissions, and note that bulk changes to private Google Tasks run without one
  3. Delete remote browser data and remote code execution data in Gemini Spark Settings after a sensitive session. Deleting a task thread or Gemini Apps activity does not remove them
  4. Keep within 15 running tasks and 50 active schedules. A schedule does not run when 15 tasks are running or the usage limit is reached
  5. Treat every safety statement here as Google's own description. None was tested, and no message was sent to the service

Leon

  1. Clone the develop branch for 2.0. npm install --global @leon-ai/cli and docs.getleon.ai install and describe the legacy 1.0 betas
  2. Set client_interface.auth.enabled: true and a LEON_PROFILE_TOKEN before the machine joins a shared network. The server binds 0.0.0.0
  3. Set telemetry_enabled: false and runtime.pulse_enabled: false in the profile config.yml for an unattended or private run
  4. Use availability.tools.allowed to limit tools. Shell, file writes, computer use and browser control are otherwise available to the agent with no approval prompt
  5. Back up LEON_CONNECTIONS_ENCRYPTION_KEY from the profile .env. Without it the stored connections cannot be read

Questions

Which is better for AI agents, Gemini Spark or Leon?

Leon scores 41 (E) on agent readiness against Gemini Spark's 24.5 (F), and leads in 5 of 7 scored categories. Gemini Spark leads on security & auth.

Are Gemini Spark and Leon open source?

No open-source release is listed for Gemini Spark. Leon is open source (MIT).

Other comparisons with Gemini Spark or Leon

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