Assertion

What is Assertion?

Assertion gives coding agents a memory that persists across sessions and across a team. A free plugin adds it to Claude Code, Cursor and Codex: while the agent works, it keeps the decisions and their reasons, such as what was tried, what failed and what was settled, rather than transcripts or source code. New sessions start from that history, and teammates who join a shared space recall each other's captured work. Assertion also offers its own coding agent for Mac with Apple Silicon, or in a terminal, that runs Claude, GPT, Gemini, Grok and Muse models on one bill and says it avoids compaction by relying on memory. A third product, Assertion Analytics in Studio, takes CSV data and returns an executed notebook and a report. Memory is private by default, visible and deletable in Studio. The plugin is free for individual developers, the agent has Builder, Pro, Max and Ultra plans from $10 a month, and Team seats are $10 per member.

Use cases

• Share coding decisions across a team's agents
• Start new coding sessions with prior context
• Avoid repeating experiments a teammate ran
• Run long coding sessions without compaction
• Analyse CSV data and deploy a decision app
• Review what an agent remembers and delete it

Who it's for

• Software developers
• Engineering teams
• Data teams
• Research and R&D groups

Why use Assertion

• Teammates' agents start from the decisions already made, so nobody re-explains or repeats an experiment.
• Memory is private until you share a space, and you can inspect and delete what was kept.
• The free plugin keeps your existing agent, including at work for individual developers.
• Your code, data and memory are not used to train models, according to the vendor.
• Included usage resets weekly, and you can upgrade any time if you run out.

Assertion features

• Free plugin for Claude Code, Cursor and Codex
• Captures decisions, findings and reasons instead of full transcripts
• Shared spaces where teammates' agents recall each other's work
• Studio view to see, check evidence for and delete stored memory
• Own coding agent for Mac and terminal with memory built in
• Claude, GPT, Gemini, Grok and Muse models on one bill
• Weekly included usage that resets each week
• Assertion Analytics for CSV analysis, notebooks, reports and live dashboards
• Plugin client published on GitHub so you can inspect what is captured

Assertion integrations

• Claude Code
• Cursor
• Codex

How to get started with Assertion

1. Install the plugin in Claude Code, Cursor or Codex, or download the Assertion agent.
2. Sign in through the browser; no key is needed, and signing in creates the account if you have none.
3. Work as usual while memory captures decisions and findings in the background.
4. Open Studio to see what was captured and recalled, and delete anything you do not want kept.
5. Add teammates to a shared space so their agents recall each other's work.

Assertion limitations

• Runs only on Apple Silicon Macs, either as a desktop app or in a terminal
• The agent cannot use your own API key; the free plugin supports your own key or subscription
• Shared spaces need a Team seat or a paid plan
• The vendor says its SOC 2 audit is not complete yet
• Customer data is hosted in the United States

Assertion pricing

Yes, Assertion has a free plan. Paid plans start at $10 per month, according to the official pricing page on 24 Oct 2026.

Assertion plans

• Plugin

  Free

  for individual developers

  • Works with Claude Code, Cursor and Codex
  • Free for one developer, including at work
  • Same memory and commands

• Builder

  $10 monthly

  $8 annually

  • $20 of model usage
  • Own coding agent
  • Shared spaces
  • Weekly usage reset

• Pro

  $30 monthly

  $24 annually

  • $60 of model usage
  • Own coding agent
  • Shared spaces

• Max

  $50 monthly

  $40 annually

  • $100 of model usage
  • Own coding agent
  • Shared spaces

• Ultra

  $100 monthly

  $80 annually

  • $200 of model usage
  • Own coding agent
  • Shared spaces

• Team

  $10 per member

  14-day trial, no seat minimum

  • Covers agent and plugin users
  • Shared memory included

• Assertion Analytics Starter

  $299/month

  Analytics is licensed annually

  • One dataset up to 10MB on the free tier
  • Notebooks and reports
  • Memory included

Plans as listed on the official pricing page on 24 Oct 2026. Prices can change and may vary by country or exclude tax. Check the official pricing page.

Assertion alternatives

The main Assertion alternatives listed on Debuly are Mem0, Zep, Letta, Claude Code, Cursor and ContextStream. The table compares pricing and platforms; order is A–Z.

1. 

   Claude Code

   Anthropic's coding agent that fixes bugs, writes tests and runs migrations from your terminal, IDE, desktop app, web or Slack.

   CodingAutomation and agentsDeveloper platforms
   PaidVisit Claude Code (official site)
2. 

   ContextStream

   Shared project memory, code search and agent coordination for AI coding tools, connected through MCP and a browser workspace.

   CodingDeveloper platformsAutomation and agents
   FreemiumVisit ContextStream (official site)
3. 

   Cursor

   AI code editor and coding agent with cloud agents, Bugbot code review and multi-provider models, sold with Grok and X plans.

   CodingAutomation and agentsDeveloper platforms
   FreemiumVisit Cursor (official site)
4. 

   Letta

   Platform, formerly MemGPT, for building stateful AI agents with persistent memory, from a terminal app, SDK or API.

   Developer platformsAutomation and agentsCoding
   FreemiumVisit Letta (official site)
5. 

   Mem0

   Memory layer for AI agents and apps, available as an open-source package or a managed platform that keeps user context across sessions.

   Developer platformsAutomation and agentsCoding
   FreemiumVisit Mem0 (official site)
6. 

   Zep

   Managed memory and context platform for AI agents, built on the Graphiti knowledge graph, with Python, TypeScript and Go SDKs.

   Developer platformsAutomation and agents
   FreemiumVisit Zep (official site)

Assertion FAQ

Sources & verification

Facts on this page come from the official sources below, each with the date we read it. Written by Debuly; the vendor did not review this page.

Image credits

• Logo: from assertion-ai.com · fetched 24 Oct 2026 · Vendor trademark, used only to identify the product; removed on request
• Cover: none collected yet, so a generated tile is shown.

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