Just vs Spines
Which Writing AI tool is better in 2026?
Just
AI-powered real-time personalization for user-facing content
Spines
AI-powered publishing platform that helps authors publish books fast
Side-by-side
Spines is the more established option (raised $29M); pricing is comparable on both sides.
| Metric | Just | Spines |
|---|---|---|
| Taglinei | AI-powered real-time personalization for user-facing content | AI-powered publishing platform that helps authors publish books fast |
| Foundedi | 2023 | 2021🏆 |
| HQi | San Francisco, US | Boynton Beach, US |
| Employeesi | 1-10 | 11-50🏆 |
| Neuron scorei | 46 | 50🏆 |
| Total fundingi | $1.7M | $29M🏆 |
| Latest roundi | Seed | Series A |
| Valuationi | — | — |
| Cheapest paid plani | Pricing not disclosed | Pricing not disclosed |
| Free plani | ✓ | ✓ |
| Free triali | ✓ | ✓ |
| Top tier pricei | Pricing not disclosed | Pricing not disclosed |
| Pricing summaryi | Free | Free |
| Categoriesi |
Capability matrix
Developer-facing capabilities and access signals for Just and Spines.
| Capability | Just | Spines |
|---|---|---|
| MCP support | ✗ | ✗ |
| Public API | ✓ | ✗ |
| Webhooks | ✗ | ✗ |
| OAuth 2.0 | ✗ | ✗ |
| SDK languages | — | — |
| Free plan | ✓ | ✓ |
| Free trial | ✓ | ✓ |
| Verified | ✗ | ✗ |
| Active deal | ✗ | ✗ |
🟢 Strengths of Just
- Newer company (2023)
🔵 Strengths of Spines
- Has raised more capital ($29M vs $1.7M)
- Higher Neuron score (50 vs 46)
- More mature (2021)
Which should you choose?
Choose Spines if price matters most — it starts at Free, which is friendlier for teams watching burn. Both AI Writing tools ship core features, so the cost delta often decides it for small teams and solo operators.
Choose Spines if you want the most established option — it has raised $29M, suggesting more runway for enterprise features, support, and long-term roadmap. For mission-critical workflows or larger teams, that stability often outweighs a lower monthly price.
Frequently asked questions
Just vs Spines — which is better?
It depends on your priority. Just is the leaner option; Spines has broader feature depth. See the side-by-side table above.
Is Just cheaper than Spines?
No — Spines's cheapest paid plan is Free, while Just's is Free.
Do Just and Spines offer free plans?
Just: Yes, has a free plan. Spines: Yes, has a free plan.
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