Spike
Email, chat, notes, and meetings presented in a conversational inbox
The visible conversational email loop is buildable, but a credible replacement needs more than the first screen. Spike earns its keep through deliverability, security, integration, so expect a weekend or multi-day build and a narrower personal scope.
Build verification: not recorded. How we judge buildability
What you give up
- sender reputation, deliverability, and suppression handling
- provider-grade deliverability
- push reliability across devices
- team routing and shared inbox rules
- abuse response and security operations
Why people still pay
Spike: Email is infrastructure. Customers pay to avoid lost messages, broken auth, spam problems, and the reputational cost of a flaky inbox.
Your build guide
The stack, security requirements, and agent rules for a focused replacement.
Before you start
- Runtime and tools: TypeScript, React and a Node server with SQLite for a single small workspace.
- Before starting: A local Node runtime, writable data directory, sample records and a documented backup/restore path.
Use these project rules and optional skill references alongside the prompt. Review each skill before adding it to your agent; the AGENTS.md export includes the same guidance.
Project rule — domain: Store Account, MessageID, InReplyTo, Thread and Draft; group primarily by message relationships and show recipients before every send even when the UI resembles chat.
Project rule — scope and recovery: Start with read-only import plus reviewed sending. Email is not instant private chat; attachments, delivery failures and external recipients must stay visible.
Project rule — acceptance: Two unrelated emails share a subject and one reply adds a recipient; keep separate threads where identifiers differ and make the new recipient obvious in the composer.
Project rule — delivery: document real setup commands and permissions; do not claim a build, accuracy level, performance result or security certification that has not been demonstrated.
Recommended skill: vercel-react-best-practices — keep the proposed React work/review views responsive and avoid unnecessary rendering or data-fetch waterfalls. Follow the maintainer's installation instructions and match its requirements to the chosen runtime.
Recommended skill: web-design-guidelines — review keyboard access, focus, validation, error recovery and the readable work/review interface or HTML report. Follow the maintainer's installation instructions and match its requirements to the chosen runtime.
Implementation plan
Phase 1
Pin the working slice and create its example input: Present one authorized mailbox as conversation-style threads while preserving email recipients, subject history and quoted-message boundaries. Confirm setup: A local Node runtime, writable data directory, sample records and a documented backup/restore path.
Phase 2
Implement persistence and write-time invariants before decorating the UI: Store Account, MessageID, InReplyTo, Thread and Draft; group primarily by message relationships and show recipients before every send even when the UI resembles chat.
Phase 3
Connect the working view to real saved state. Use migrations and server-side validation; expose saved, pending and failed states. Keep each write atomic and reject stale edits using a revision number.
Phase 4
Expose the app-specific limits and recovery path in context: Start with read-only import plus reviewed sending. Email is not instant private chat; attachments, delivery failures and external recipients must stay visible.
Phase 5
Walk through this concrete acceptance case and preserve its exported evidence: Two unrelated emails share a subject and one reply adds a recipient; keep separate threads where identifiers differ and make the new recipient obvious in the composer. Finish the README and backup/restore instructions; report unfinished capabilities explicitly.
Build the following focused alternative to Spike. This is a deliberately limited personal or small-team substitute, not parity with the paid service. WORKING SLICE Present one authorized mailbox as conversation-style threads while preserving email recipients, subject history and quoted-message boundaries. SETUP AND ARCHITECTURE Use TypeScript, React and a Node server with SQLite for a single small workspace. Prerequisites: A local Node runtime, writable data directory, sample records and a documented backup/restore path. Before integrating anything, record actual versions and permissions, plus model files or provider limits only where used, in the README; make unavailable dependencies visible rather than simulating success. DOMAIN MODEL AND INVARIANTS Store Account, MessageID, InReplyTo, Thread and Draft; group primarily by message relationships and show recipients before every send even when the UI resembles chat. IMPLEMENTATION CONTRACT Use migrations and server-side validation; expose saved, pending and failed states. Keep each write atomic and reject stale edits using a revision number. Provide an input/setup view, the main work view, and a review/export view appropriate to this workflow. Preserve the last saved state if a job or save fails. Include empty, loading, permission-denied, partial and retryable-error states. Log identifiers and error categories without secret values or unnecessary private content. APP-SPECIFIC BOUNDARY AND RECOVERY Start with read-only import plus reviewed sending. Email is not instant private chat; attachments, delivery failures and external recipients must stay visible. ACCEPTANCE SCENARIO Two unrelated emails share a subject and one reply adds a recipient; keep separate threads where identifiers differ and make the new recipient obvious in the composer. Also reopen the app after an interrupted operation, confirm the saved record/export remains inspectable, and document the recovery action. These are implementation acceptance requirements, not a claim that this guide has been tested. DELIVERY Deliver a runnable repository with migrations or project-format versioning, a non-sensitive example, environment/permission setup, the exact manual acceptance steps, and a backup/export-and-restore walkthrough. Implement the working slice before optional integrations; list any deferred paid-product capabilities honestly. Do not add capabilities outside the working slice just to resemble the original product. PROJECT RULES FOR AGENTS.md Keep the domain invariants above executable at the write boundary. Propose scope changes before adding providers or permissions. Never fabricate source evidence, publish results, identity matches or successful delivery. Preserve user originals and require an explicit confirmation for destructive changes or external publication.
$ open in your agent (prompt prefilled, you press enter), copy the prompt or copy or download AGENTS.md · generated from this app's build plan
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Spike pricing
| plan | monthly | annual (per mo) | what you get |
|---|---|---|---|
| teamspace starter | $0/workspace | $0/workspace | Up to 3 members, 1 teamspace, free email address, 60 days search, 15 GB storage/member, 15 MB file uploads, 10 AI queries. |
| teamspace team | — | $4/user | 100 GB storage/member, 100 MB file uploads, unlimited search history, shared inbox; annual plan includes custom domain free for 1 year.Public page showed annual per-member pricing; monthly price was not exposed in crawled text. |
| teamspace business | — | $8/user | 1 TB storage/member, 500 MB file uploads, unlimited search history, 50 video participants; SAML listed as coming soon.Public page showed annual per-member pricing; monthly price was not exposed in crawled text. |
| email app free | $0/user | $0/user | 1 email address, 1 GB storage, 30 MB file uploads, 60 days search, 1:1 calls, 10 AI queries. |
| email app pro | — | $6/user | Up to 3 email addresses, 5 participants, 5 GB storage, 100 MB file uploads, unlimited search.Annual pricing only exposed. |
| email app ultimate | — | $12/user | Unlimited email addresses, 10 participants, 20 GB storage, 1 GB file uploads.Annual pricing only exposed. |
free tierTeamspace Starter: 3 members, 1 teamspace, 60-day search, 15 GB/member, 15 MB uploads, 10 AI queries; Email Free: 1 email address, 1 GB storage, 30 MB uploads, 60-day search, 10 AI queries.
billingannual public pricing only; subscriptions auto-renew until canceled
hidden costsMonthly USD prices were not exposed on the official page; Teamspace storage/file limits differ from Email App limits.
pricing sources checked 2026-08-10 · pricing source ↗
Questions about Spike
Can you build your own Spike with AI?
Partly. The visible conversational email loop is buildable, but a credible replacement needs more than the first screen. Spike earns its keep through deliverability, security, integration, so expect a weekend or multi-day build and a narrower personal scope.
What does the Spike build prompt cover?
The prompt starts with this scope: Present one authorized mailbox as conversation-style threads while preserving email recipients, subject history and quoted-message boundaries. Full-product capabilities excluded from the comparison include: sender reputation, deliverability, and suppression handling; provider-grade deliverability; push reliability across devices. Follow the implementation plan and its prerequisites before expanding the build.
How do I use the prompt, AGENTS.md and agent skills?
Start with the Spike prerequisites and stack, then copy the prompt into your coding agent. Save the project rules as AGENTS.md in the project root. Linked skills are optional packages or source instructions for specific tasks; review their current contents and install only those matching the chosen stack. A skill does not supply API credentials or verify the finished app.
How long will this Spike project take?
The catalogue estimate is weekend to multi-day for the limited scope. Setup, integration approvals, debugging, deployment and ongoing maintenance can add time. This is an estimate, not a delivery guarantee.
What would I give up by replacing Spike?
sender reputation, deliverability, and suppression handling; provider-grade deliverability; push reliability across devices; team routing and shared inbox rules; abuse response and security operations. Spike: Email is infrastructure. Customers pay to avoid lost messages, broken auth, spam problems, and the reputational cost of a flaky inbox.
What can I use instead of building Spike?
The prior-art section lists Mailspring as starting points. Review their current scope, license and maintenance before adopting one.