diff --git a/api/lib/env.ts b/api/lib/env.ts
index b52700a..1f5169e 100644
--- a/api/lib/env.ts
+++ b/api/lib/env.ts
@@ -39,3 +39,8 @@ export const CLICKHOUSE_PASSWORD = env.CLICKHOUSE_PASSWORD
 if (!CLICKHOUSE_PASSWORD) {
   throw Error('CLICKHOUSE_PASSWORD: field required in the env')
 }
+
+// Optional interval (ms) for refreshing external SQL database schemas
+// Defaults to 24 hours
+export const DB_SCHEMA_REFRESH_MS = Number(env.DB_SCHEMA_REFRESH_MS) ||
+  24 * 60 * 60 * 1000
diff --git a/api/routes.ts b/api/routes.ts
index 58f838d..e7b20a2 100644
--- a/api/routes.ts
+++ b/api/routes.ts
@@ -2,6 +2,7 @@ import { makeRouter, route } from '/api/lib/router.ts'
 import type { RequestContext } from '/api/lib/context.ts'
 import { handleGoogleCallback, initiateGoogleAuth } from './auth.ts'
 import {
+  DatabaseSchemasCollection,
   DeploymentDef,
   DeploymentsCollection,
   ProjectsCollection,
@@ -333,6 +334,37 @@ const defs = {
     output: deploymentOutput,
     description: 'Regenerate a deployment token',
   }),
+  'GET/api/deployment/schema': route({
+    authorize: withUserSession,
+    fn: (_ctx, { url }) => {
+      const dep = DeploymentsCollection.get(url)
+      if (!dep) throw respond.NotFound({ message: 'Deployment not found' })
+      if (!dep.databaseEnabled) {
+        throw respond.BadRequest({
+          message: 'Database not enabled for deployment',
+        })
+      }
+      const schema = DatabaseSchemasCollection.get(url)
+      if (!schema) throw respond.NotFound({ message: 'Schema not cached yet' })
+      return schema
+    },
+    input: OBJ({ url: STR('Deployment URL') }),
+    output: OBJ({
+      deploymentUrl: STR('Deployment url (matches deployment.url)'),
+      dialect: STR('Detected SQL dialect'),
+      refreshedAt: STR('ISO datetime of last refresh'),
+      tables: ARR(OBJ({
+        columns: ARR(OBJ({
+          name: STR('Column name'),
+          type: STR('Column data type'),
+          ordinal: NUM('Column ordinal position'),
+        })),
+        schema: optional(STR('Schema name')),
+        table: STR('Table name'),
+      })),
+    }, 'Database schema cache for a deployment'),
+    description: 'Get cached database schema for a deployment',
+  }),
   'DELETE/api/deployment': route({
     authorize: withAdminSession,
     fn: async (_ctx, input) => {
diff --git a/api/schema.ts b/api/schema.ts
index 78da210..959ad69 100644
--- a/api/schema.ts
+++ b/api/schema.ts
@@ -1,4 +1,4 @@
-import { ARR, BOOL, OBJ, optional, STR } from './lib/validator.ts'
+import { ARR, BOOL, NUM, OBJ, optional, STR } from './lib/validator.ts'
 import { Asserted } from './lib/router.ts'
 import { createCollection } from './lib/json_store.ts'
 
@@ -39,6 +39,25 @@ export const DeploymentDef = OBJ({
 }, 'The deployment schema definition')
 export type Deployment = Asserted<typeof DeploymentDef>
 
+// A flattened representation of a remote SQL database logical schema for a deployment
+// "dialect" is a best-effort detection (postgres | mysql | sqlite | sqlserver | oracle | duckdb | unknown)
+// "tables" is a JSON stringified array of { schema?, table, columns: [{ name, type, ordinal }] }
+export const DatabaseSchemaDef = OBJ({
+  deploymentUrl: STR('Deployment url (matches deployment.url)'),
+  dialect: STR('Detected SQL dialect'),
+  refreshedAt: STR('ISO datetime of last refresh'),
+  tables: ARR(OBJ({
+    columns: ARR(OBJ({
+      name: STR(),
+      type: STR(),
+      ordinal: NUM(),
+    })),
+    schema: optional(STR()),
+    table: STR(),
+  })),
+}, 'Database schema cache for a deployment')
+export type DatabaseSchema = Asserted<typeof DatabaseSchemaDef>
+
 export const UsersCollection = await createCollection<User, 'userEmail'>(
   { name: 'users', primaryKey: 'userEmail' },
 )
@@ -60,3 +79,8 @@ export const DeploymentsCollection = await createCollection<
 >(
   { name: 'deployments', primaryKey: 'url' },
 )
+
+export const DatabaseSchemasCollection = await createCollection<
+  DatabaseSchema,
+  'deploymentUrl'
+>({ name: 'db_schemas', primaryKey: 'deploymentUrl' })
diff --git a/api/server.ts b/api/server.ts
index 3460aef..a5ec8c1 100644
--- a/api/server.ts
+++ b/api/server.ts
@@ -9,6 +9,7 @@ import { type RequestContext, requestContext } from '/api/lib/context.ts'
 import { join } from 'jsr:@std/path/join'
 import { serveDir } from 'jsr:@std/http/file-server'
 import { PORT } from './lib/env.ts'
+import { startSchemaRefreshLoop } from './sql.ts'
 
 const isProd = Deno.args.includes('--env=prod')
 const staticDir = isProd
@@ -97,6 +98,13 @@ export const fetch = async (req: Request) => {
 
 log.info('server-start')
 
+// Start periodic DB schema refresh (non-blocking)
+try {
+  startSchemaRefreshLoop()
+} catch (err) {
+  log.error('schema-loop-start-failed', { err })
+}
+
 Deno.serve({
   port: PORT,
 }, fetch)
diff --git a/api/sql.ts b/api/sql.ts
new file mode 100644
index 0000000..f58724c
--- /dev/null
+++ b/api/sql.ts
@@ -0,0 +1,131 @@
+import { DatabaseSchemasCollection, DeploymentsCollection } from './schema.ts'
+import { DB_SCHEMA_REFRESH_MS } from './lib/env.ts'
+import { log } from './lib/log.ts'
+
+async function runSQL(
+  endpoint: string,
+  token: string,
+  query: string,
+  params?: unknown,
+) {
+  const res = await fetch(endpoint, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      Authorization: `Bearer ${token}`,
+    },
+    body: JSON.stringify({ query, params }),
+  })
+  if (!res.ok) throw Error(`sql endpoint error ${res.status}`)
+  const data = await res.json()
+
+  return data
+}
+
+// Dialect detection attempts (run first successful)
+const DETECTION_QUERIES: { name: string; sql: string; matcher: RegExp }[] = [
+  {
+    name: 'sqlite',
+    sql: 'SELECT sqlite_version() as v',
+    matcher: /\d+\.\d+\.\d+/,
+  },
+]
+
+async function detectDialect(endpoint: string, token: string): Promise<string> {
+  for (const d of DETECTION_QUERIES) {
+    try {
+      const rows = await runSQL(endpoint, token, d.sql)
+      log.debug('dialect-detection', { dialect: d.name, rows })
+      if (rows.length) {
+        const text = JSON.stringify(rows[0])
+        if (d.matcher.test(text)) return d.name
+      }
+    } catch { /* ignore */ }
+  }
+  return 'unknown'
+}
+
+// Introspection queries per dialect returning columns list
+// Standardized output fields: table_schema (nullable), table_name, column_name, data_type, ordinal_position
+const INTROSPECTION: Record<string, string> = {
+  sqlite:
+    `SELECT NULL AS table_schema, m.name AS table_name, p.name AS column_name, p.type AS data_type, p.cid + 1 AS ordinal_position FROM sqlite_master m JOIN pragma_table_info(m.name) p WHERE m.type = 'table' AND m.name NOT LIKE 'sqlite_%' ORDER BY m.name, p.cid`,
+  unknown:
+    `SELECT table_schema, table_name, column_name, data_type, ordinal_position FROM information_schema.columns ORDER BY table_schema, table_name, ordinal_position`,
+}
+
+async function fetchSchema(endpoint: string, token: string, dialect: string) {
+  const sql = INTROSPECTION[dialect] ?? INTROSPECTION.unknown
+  return await runSQL(endpoint, token, sql)
+}
+
+type ColumnInfo = { name: string; type: string; ordinal: number }
+type TableInfo = {
+  schema: string | undefined
+  table: string
+  columns: ColumnInfo[]
+}
+
+export async function refreshOneSchema(
+  dep: ReturnType<typeof DeploymentsCollection.get>,
+) {
+  if (!dep || !dep.databaseEnabled || !dep.sqlEndpoint || !dep.sqlToken) return
+  try {
+    const dialect = await detectDialect(dep.sqlEndpoint, dep.sqlToken)
+    const rows = await fetchSchema(dep.sqlEndpoint, dep.sqlToken, dialect)
+    // group rows
+    const tableMap = new Map<string, TableInfo>()
+    for (const r of rows) {
+      const schema = (r.table_schema as string) || undefined
+      const table = r.table_name as string
+      if (!table) continue
+      const key = (schema ? schema + '.' : '') + table
+      if (!tableMap.has(key)) tableMap.set(key, { schema, table, columns: [] })
+      tableMap.get(key)!.columns.push({
+        name: String(r.column_name),
+        type: String(r.data_type || ''),
+        ordinal: Number(r.ordinal_position || 0),
+      })
+    }
+    const tables = [...tableMap.values()].map((t) => ({
+      ...t,
+      columns: t.columns.sort((a, b) => a.ordinal - b.ordinal),
+    }))
+    const payload = {
+      deploymentUrl: dep.url,
+      dialect,
+      refreshedAt: new Date().toISOString(),
+      tables: tables,
+    }
+    const existing = DatabaseSchemasCollection.get(dep.url)
+    if (existing) {
+      await DatabaseSchemasCollection.update(dep.url, payload)
+    } else {
+      await DatabaseSchemasCollection.insert(payload)
+    }
+    log.info('schema-refreshed', {
+      deployment: dep.url,
+      dialect,
+      tables: tables.length,
+    })
+  } catch (err) {
+    log.error('schema-refresh-failed', { deployment: dep.url, err })
+  }
+}
+
+export async function refreshAllSchemas() {
+  for (const dep of DeploymentsCollection.values()) {
+    await refreshOneSchema(dep)
+  }
+}
+
+let intervalHandle: number | undefined
+export function startSchemaRefreshLoop() {
+  if (intervalHandle) return
+  // initial kick (non-blocking)
+  refreshAllSchemas()
+  intervalHandle = setInterval(() => {
+    refreshAllSchemas()
+  }, DB_SCHEMA_REFRESH_MS) as unknown as number
+  log.info('schema-refresh-loop-started', { everyMs: DB_SCHEMA_REFRESH_MS })
+}