Tonic Fabricate Alternative: Seedfast vs Fabricate

Tonic Fabricate and Seedfast do the same core job: generate relational data from a schema, without copying production, and both can read a live database to do it. So the choice between them isn't about whose data is safer or which one is schema-aware — it's about where the tool runs and how you pay. Seedfast is a Postgres CLI you drop into CI on a flat plan; Fabricate is a web agent you drive through chat, an SDK, or an API, billed per generation turn. If you've tried Fabricate and now want a Tonic Fabricate alternative that runs as one CLI command against your Postgres database in a pipeline, this is the head-to-head.

Three things set Seedfast apart. Because it's CLI-first and MCP-native, a single command seeds your Postgres database inside a pipeline, and that same run doubles as an MCP tool any AI coding agent can call. Pricing is flat, with no per-token metering, so the cost holds whether you seed once or on every build. And on Postgres and the foreign-key graph, it goes deep. Fabricate is the other shape entirely: a web and chat agent, reached through an SDK or API, billed per generation turn, with broader database coverage. What the two share, generating without production data and reading a live schema, won't decide it. Those three will.

Tonic Fabricate is Tonic.ai's synthetic-data product, distinct from Tonic Structural, their production-data de-identification platform. Point it at a schema, a handful of sample rows, or a plain-language prompt, and it generates relational data on demand, sketching a multi-step plan first when the model is large or complex. Its reach is wide: live database connections, generation into Postgres, MySQL, Oracle, and Databricks, plus exports to Parquet, Avro, and JSON. That breadth matters. Seedfast is Postgres-only, so when your work spans several engines or needs those export targets, Fabricate is the better choice and Seedfast won't keep up. In a browser, for interactive, exploratory generation, it's a strong tool.

With Seedfast, you point a CLI at a Postgres connection string; it reads the live schema and foreign-key graph and seeds the database in a single run:

seedfast seed --scope "fintech app with 100 accounts, transactions, and varied balances"
  → Connected to PostgreSQL
  → Found 34 tables, 67 foreign keys
  → Generating data...
  → Done. Seeded 12,847 rows in 6.3s

It reads the live schema on every run, walks the foreign keys, inserts parents before children, and handles circular foreign keys. A migration that adds a table or column is picked up automatically, and the same command is exposed as an MCP tool, so an AI coding agent can run it directly.

Fabricate reaches a seeded database differently. Its CLI bulk-loads already-generated data into a Postgres target; it doesn't read your live schema and seed in one step, so the seed-after-migration loop runs through the web agent or an SDK/API integration, with no advertised MCP support. For a CI/CD pipeline, that's the difference that decides it: a single unattended command, or a service call.

Both tools generate without production data and both read a live schema; they split on interface, the CI seed step, MCP, database breadth, and pricing.

Fabricate's wider database and export coverage — the bolded row — is the honest trade-off. For the Postgres-in-CI case, the one-command CLI with flat pricing is where Seedfast pulls ahead.

Fabricate's pricing (tonic.ai/pricing, confirmed 2026-06-24) runs on generation credits plus token usage:

• Free: $0/month with $10/month in credits — about nine highly complex, multi-step sessions, per Tonic.
• Plus: $29/month, including $25/month in credits, then pay-as-you-go.
• Pay-as-you-go: roughly $0.17 per standard turn and $0.37 per complex turn.
• Enterprise: custom pricing, with pooled usage, SSO, RBAC, and self-host options.

Prices drift, but the model is the point: Fabricate meters generation, so every turn past your monthly credits costs tokens. That suits occasional, interactive use in a browser, and it gets hard to budget once a CI build seeds on every run.

Fabricate does offer a lever Seedfast doesn't: on Enterprise plans you can bring your own Anthropic or Amazon Bedrock LLM key and choose the model that actually generates the data, which gives you control over output quality. It also moves the cost around: with your own key, Tonic stops billing for AI usage and you pay the LLM provider directly, so the model you pick sets the price of a run — a strong, more capable model raises the bill. It's a genuine plus, and one more variable to forecast (Enterprise; as of June 2026, per Tonic's Fabricate docs).

Seedfast charges a flat rate — run the seed once or on every build and the plan cost doesn't move — the one axis a credit-and-token model can't match. See pricing for current terms.

Pick Seedfast if you're on Postgres and want one CLI command that seeds your live schema in CI, on a flat plan, with MCP support for AI coding agents. It goes deep on Postgres and its foreign-key graph instead of spreading across many engines.

Pick Fabricate if you want a polished web and chat agent, generate across several database engines, or need exotic export formats. Its multi-database breadth and interactive experience are real strengths.

Cross-shopping wider than these two? The best Postgres test data generator guide ranks tools on schema-awareness and CI fit, data seeding tools covers the regulated-industry angle, and Tonic Fabricate vs Mockaroo sets both against a Postgres CLI. Other alternatives: GenRocket, Mockaroo, Snaplet Seed, and Neosync.

Yes — Seedfast. The command is seedfast seed --scope "...": it connects to a Postgres database, reads the schema and foreign keys, writes referentially valid rows in one run, and exposes that run as an MCP tool. Fabricate's CLI bulk-loads data you've already generated, so the live-schema seed itself still happens in its web agent or through an API.

Add one step after your migrations: seedfast seed with a connection string and a --scope. It re-reads the schema on that run, inserts referentially valid rows before the test suite starts, and exits non-zero on failure so the build gate works. The CI/CD database seeding guide has the full setup, with stack walkthroughs for seeding a Supabase database and seeding a Neon database.

It's a credit-and-token model: $10/month in credits on the free tier, $29/month with $25 in credits on Plus, then pay-as-you-go at about $0.17 per standard turn and $0.37 per complex turn (confirmed June 2026 — re-check before budgeting). The practical contrast with Seedfast's flat plan is forecastability: Fabricate's bill scales with how much you generate, so a generator running on every CI build is hard to budget.

$0/month with $10/month in generation credits — about nine highly complex, multi-step sessions, per Tonic — enough to evaluate the browser experience. Seedfast's 30-day free trial covers small development datasets, run as a CLI command against your own Postgres database rather than in a web UI.

Want a live-schema read, a CLI step in CI, and a flat plan? Seedfast connects to your PostgreSQL database, reads the schema and foreign-key graph, and generates connected, realistic data in one command — no schema to paste, no per-token metering, and a free 30-day trial to start. Run your first seed in about two minutes, see pricing, or watch the one-command demo.

Related guides:

• Best Postgres Test Data Generator: the broader buyer comparison
• Data Seeding Tools for Regulated Teams: the compliance-angle category comparison
• Tonic Fabricate vs Mockaroo: both set against a one-command Postgres CLI
• GenRocket, Mockaroo, Snaplet Seed, and Neosync: the other alternatives