diff --git a/docs/docs/api.md b/docs/docs/api.md
index a8ac18fe..1cea6027 100644
--- a/docs/docs/api.md
+++ b/docs/docs/api.md
@@ -567,6 +567,64 @@ $ curl https://manifold.markets/api/v0/market/{marketId}/resolve -X POST \
                  ]}'
 ```
 
+### `GET /v0/bets`
+
+Gets a list of bets, ordered by creation date descending.
+
+Parameters:
+
+- `username`: Optional. If set, the response will include only bets created by this user.
+- `market`: Optional. The slug of a market. If set, the response will only include bets on this market.
+- `limit`: Optional. How many bets to return. The maximum and the default is 1000.
+- `before`: Optional. The ID of the bet before which the list will start. For
+  example, if you ask for the most recent 10 bets, and then perform a second
+  query for 10 more bets with `before=[the id of the 10th bet]`, you will
+  get bets 11 through 20.
+
+Requires no authorization.
+
+- Example request
+  ```
+  https://manifold.markets/api/v0/bets?username=ManifoldMarkets&market=will-california-abolish-daylight-sa
+  ```
+- Response type: A `Bet[]`.
+
+- <details><summary>Example response</summary><p>
+
+  ```json
+  [
+    {
+      "probAfter": 0.44418877319153904,
+      "shares": -645.8346334931828,
+      "outcome": "YES",
+      "contractId": "tgB1XmvFXZNhjr3xMNLp",
+      "sale": {
+        "betId": "RcOtarI3d1DUUTjiE0rx",
+        "amount": 474.9999999999998
+      },
+      "createdTime": 1644602886293,
+      "userId": "94YYTk1AFWfbWMpfYcvnnwI1veP2",
+      "probBefore": 0.7229189477449224,
+      "id": "x9eNmCaqQeXW8AgJ8Zmp",
+      "amount": -499.9999999999998
+    },
+    {
+      "probAfter": 0.9901970375647697,
+      "contractId": "zdeaYVAfHlo9jKzWh57J",
+      "outcome": "YES",
+      "amount": 1,
+      "id": "8PqxKYwXCcLYoXy2m2Nm",
+      "shares": 1.0049875638533763,
+      "userId": "94YYTk1AFWfbWMpfYcvnnwI1veP2",
+      "probBefore": 0.9900000000000001,
+      "createdTime": 1644705818872
+    }
+  ]
+  ```
+
+  </p>
+  </details>
+
 ## Changelog
 
 - 2022-06-08: Add paging to markets endpoint
diff --git a/firestore.indexes.json b/firestore.indexes.json
index e0cee632..0a8b14bd 100644
--- a/firestore.indexes.json
+++ b/firestore.indexes.json
@@ -559,6 +559,28 @@
           "queryScope": "COLLECTION_GROUP"
         }
       ]
+    },
+    {
+      "collectionGroup": "bets",
+      "fieldPath": "id",
+      "indexes": [
+        {
+          "order": "ASCENDING",
+          "queryScope": "COLLECTION"
+        },
+        {
+          "order": "DESCENDING",
+          "queryScope": "COLLECTION"
+        },
+        {
+          "arrayConfig": "CONTAINS",
+          "queryScope": "COLLECTION"
+        },
+        {
+          "order": "ASCENDING",
+          "queryScope": "COLLECTION_GROUP"
+        }
+      ]
     }
   ]
 }
diff --git a/web/lib/firebase/bets.ts b/web/lib/firebase/bets.ts
index c442ff73..6fc29d24 100644
--- a/web/lib/firebase/bets.ts
+++ b/web/lib/firebase/bets.ts
@@ -4,6 +4,13 @@ import {
   query,
   where,
   orderBy,
+  QueryConstraint,
+  limit,
+  startAfter,
+  doc,
+  getDocs,
+  getDoc,
+  DocumentSnapshot,
 } from 'firebase/firestore'
 import { uniq } from 'lodash'
 
@@ -78,6 +85,43 @@ export async function getUserBets(
     .catch((reason) => reason)
 }
 
+export async function getBets(options: {
+  userId?: string
+  contractId?: string
+  before?: string
+  limit: number
+}) {
+  const { userId, contractId, before } = options
+
+  const queryParts: QueryConstraint[] = [
+    orderBy('createdTime', 'desc'),
+    limit(options.limit),
+  ]
+  if (userId) {
+    queryParts.push(where('userId', '==', userId))
+  }
+  if (before) {
+    let beforeSnap: DocumentSnapshot
+    if (contractId) {
+      beforeSnap = await getDoc(
+        doc(db, 'contracts', contractId, 'bets', before)
+      )
+    } else {
+      beforeSnap = (
+        await getDocs(
+          query(collectionGroup(db, 'bets'), where('id', '==', before))
+        )
+      ).docs[0]
+    }
+    queryParts.push(startAfter(beforeSnap))
+  }
+
+  const querySource = contractId
+    ? collection(db, 'contracts', contractId, 'bets')
+    : collectionGroup(db, 'bets')
+  return await getValues<Bet>(query(querySource, ...queryParts))
+}
+
 export async function getContractsOfUserBets(userId: string) {
   const bets: Bet[] = await getUserBets(userId, { includeRedemptions: false })
   const contractIds = uniq(bets.map((bet) => bet.contractId))
diff --git a/web/pages/api/v0/_types.ts b/web/pages/api/v0/_types.ts
index e0012c2b..7f52077d 100644
--- a/web/pages/api/v0/_types.ts
+++ b/web/pages/api/v0/_types.ts
@@ -55,6 +55,18 @@ export type ApiError = {
   error: string
 }
 
+type ValidationErrorDetail = {
+  field: string | null
+  error: string
+}
+export class ValidationError {
+  details: ValidationErrorDetail[]
+
+  constructor(details: ValidationErrorDetail[]) {
+    this.details = details
+  }
+}
+
 export function toLiteMarket(contract: Contract): LiteMarket {
   const {
     id,
diff --git a/web/pages/api/v0/_validate.ts b/web/pages/api/v0/_validate.ts
new file mode 100644
index 00000000..25f5af4e
--- /dev/null
+++ b/web/pages/api/v0/_validate.ts
@@ -0,0 +1,17 @@
+import { z } from 'zod'
+import { ValidationError } from './_types'
+
+export const validate = <T extends z.ZodTypeAny>(schema: T, val: unknown) => {
+  const result = schema.safeParse(val)
+  if (!result.success) {
+    const issues = result.error.issues.map((i) => {
+      return {
+        field: i.path.join('.') || null,
+        error: i.message,
+      }
+    })
+    throw new ValidationError(issues)
+  } else {
+    return result.data as z.infer<T>
+  }
+}
diff --git a/web/pages/api/v0/bets.ts b/web/pages/api/v0/bets.ts
new file mode 100644
index 00000000..c3de3e97
--- /dev/null
+++ b/web/pages/api/v0/bets.ts
@@ -0,0 +1,66 @@
+import { NextApiRequest, NextApiResponse } from 'next'
+import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
+import { Bet, getBets } from 'web/lib/firebase/bets'
+import { getContractFromSlug } from 'web/lib/firebase/contracts'
+import { getUserByUsername } from 'web/lib/firebase/users'
+import { ApiError, ValidationError } from './_types'
+import { z } from 'zod'
+import { validate } from './_validate'
+
+const queryParams = z
+  .object({
+    username: z.string().optional(),
+    market: z.string().optional(),
+    limit: z
+      .number()
+      .default(1000)
+      .or(z.string().regex(/\d+/).transform(Number))
+      .refine((n) => n >= 0 && n <= 1000, 'Limit must be between 0 and 1000'),
+    before: z.string().optional(),
+  })
+  .strict()
+
+export default async function handler(
+  req: NextApiRequest,
+  res: NextApiResponse<Bet[] | ValidationError | ApiError>
+) {
+  await applyCorsHeaders(req, res, CORS_UNRESTRICTED)
+
+  let params: z.infer<typeof queryParams>
+  try {
+    params = validate(queryParams, req.query)
+  } catch (e) {
+    if (e instanceof ValidationError) {
+      return res.status(400).json(e)
+    }
+    console.error(`Unknown error during validation: ${e}`)
+    return res.status(500).json({ error: 'Unknown error during validation' })
+  }
+
+  const { username, market, limit, before } = params
+
+  let userId: string | undefined
+  if (username) {
+    const user = await getUserByUsername(username)
+    if (!user) {
+      res.status(404).json({ error: 'User not found' })
+      return
+    }
+    userId = user.id
+  }
+
+  let contractId: string | undefined
+  if (market) {
+    const contract = await getContractFromSlug(market)
+    if (!contract) {
+      res.status(404).json({ error: 'Contract not found' })
+      return
+    }
+    contractId = contract.id
+  }
+
+  const bets = await getBets({ userId, contractId, limit, before })
+
+  res.setHeader('Cache-Control', 'max-age=0')
+  return res.status(200).json(bets)
+}
diff --git a/web/pages/api/v0/markets.ts b/web/pages/api/v0/markets.ts
index fec3cc30..56ecc594 100644
--- a/web/pages/api/v0/markets.ts
+++ b/web/pages/api/v0/markets.ts
@@ -2,38 +2,40 @@
 import type { NextApiRequest, NextApiResponse } from 'next'
 import { listAllContracts } from 'web/lib/firebase/contracts'
 import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
-import { toLiteMarket } from './_types'
+import { toLiteMarket, ValidationError } from './_types'
+import { z } from 'zod'
+import { validate } from './_validate'
+
+const queryParams = z
+  .object({
+    limit: z
+      .number()
+      .default(1000)
+      .or(z.string().regex(/\d+/).transform(Number))
+      .refine((n) => n >= 0 && n <= 1000, 'Limit must be between 0 and 1000'),
+    before: z.string().optional(),
+  })
+  .strict()
 
 export default async function handler(
   req: NextApiRequest,
   res: NextApiResponse
 ) {
   await applyCorsHeaders(req, res, CORS_UNRESTRICTED)
-  let before: string | undefined
-  let limit: number | undefined
-  if (req.query.before != null) {
-    if (typeof req.query.before !== 'string') {
-      res.status(400).json({ error: 'before must be null or a market ID.' })
-      return
+
+  let params: z.infer<typeof queryParams>
+  try {
+    params = validate(queryParams, req.query)
+  } catch (e) {
+    if (e instanceof ValidationError) {
+      return res.status(400).json(e)
     }
-    before = req.query.before
-  }
-  if (req.query.limit != null) {
-    if (typeof req.query.limit !== 'string') {
-      res
-        .status(400)
-        .json({ error: 'limit must be null or a number of markets to return.' })
-      return
-    }
-    limit = parseInt(req.query.limit)
-  } else {
-    limit = 1000
-  }
-  if (limit < 1 || limit > 1000) {
-    res.status(400).json({ error: 'limit must be between 1 and 1000.' })
-    return
+    console.error(`Unknown error during validation: ${e}`)
+    return res.status(500).json({ error: 'Unknown error during validation' })
   }
 
+  const { limit, before } = params
+
   try {
     const contracts = await listAllContracts(limit, before)
     // Serve from Vercel cache, then update. see https://vercel.com/docs/concepts/functions/edge-caching
diff --git a/web/pages/api/v0/user/[username]/bets/index.ts b/web/pages/api/v0/user/[username]/bets/index.ts
new file mode 100644
index 00000000..464af52c
--- /dev/null
+++ b/web/pages/api/v0/user/[username]/bets/index.ts
@@ -0,0 +1,25 @@
+import { NextApiRequest, NextApiResponse } from 'next'
+import { applyCorsHeaders, CORS_UNRESTRICTED } from 'web/lib/api/cors'
+import { Bet, getUserBets } from 'web/lib/firebase/bets'
+import { getUserByUsername } from 'web/lib/firebase/users'
+import { ApiError } from '../../../_types'
+
+export default async function handler(
+  req: NextApiRequest,
+  res: NextApiResponse<Bet[] | ApiError>
+) {
+  await applyCorsHeaders(req, res, CORS_UNRESTRICTED)
+  const { username } = req.query
+
+  const user = await getUserByUsername(username as string)
+
+  if (!user) {
+    res.status(404).json({ error: 'User not found' })
+    return
+  }
+
+  const bets = await getUserBets(user.id, { includeRedemptions: false })
+
+  res.setHeader('Cache-Control', 'max-age=0')
+  return res.status(200).json(bets)
+}