diff --git a/nimbus/db/backends/lmdb_backend.nim b/nimbus/db/backends/lmdb_backend.nim
new file mode 100644
index 000000000..dcfbb019a
--- /dev/null
+++ b/nimbus/db/backends/lmdb_backend.nim
@@ -0,0 +1,160 @@
+import os, ranges, eth_trie/[defs, db_tracing]
+import ../storage_types
+
+when defined(windows):
+  const Lib = "lmdb.dll"
+elif defined(macos):
+  const Lib = "liblmdb.dylib"
+else:
+  const Lib = "liblmdb.so"
+
+const
+  MDB_NOSUBDIR = 0x4000
+  MDB_NOTFOUND = -30798
+  LMDB_MAP_SIZE = 1024 * 1024 * 1024 * 10  # 10TB enough?
+
+type
+  MDB_Env = distinct pointer
+  MDB_Txn = distinct pointer
+  MDB_Dbi = distinct cuint
+
+  MDB_val = object
+    mv_size: csize
+    mv_data: pointer
+
+# this is only a subset of LMDB API needed in nimbus
+proc mdb_env_create(env: var MDB_Env): cint {.cdecl, dynlib: Lib, importc: "mdb_env_create".}
+proc mdb_env_open(env: MDB_Env, path: cstring, flags: cuint, mode: cint): cint {.cdecl, dynlib: Lib, importc: "mdb_env_open".}
+proc mdb_txn_begin(env: MDB_Env, parent: MDB_Txn, flags: cuint, txn: var MDB_Txn): cint {.cdecl, dynlib: Lib, importc: "mdb_txn_begin".}
+proc mdb_txn_commit(txn: MDB_Txn): cint {.cdecl, dynlib: Lib, importc: "mdb_txn_commit".}
+proc mdb_dbi_open(txn: MDB_Txn, name: cstring, flags: cuint, dbi: var MDB_Dbi): cint {.cdecl, dynlib: Lib, importc: "mdb_dbi_open".}
+proc mdb_dbi_close(env: MDB_Env, dbi: MDB_Dbi) {.cdecl, dynlib: Lib, importc: "mdb_dbi_close".}
+proc mdb_env_close(env: MDB_Env) {.cdecl, dynlib: Lib, importc: "mdb_env_close".}
+
+proc mdb_get(txn: MDB_Txn, dbi: MDB_Dbi, key: var MDB_val, data: var MDB_val): cint {.cdecl, dynlib: Lib, importc: "mdb_get".}
+proc mdb_del(txn: MDB_Txn, dbi: MDB_Dbi, key: var MDB_val, data: ptr MDB_val): cint {.cdecl, dynlib: Lib, importc: "mdb_del".}
+proc mdb_put(txn: MDB_Txn, dbi: MDB_Dbi, key: var MDB_val, data: var MDB_val, flags: cuint): cint {.cdecl, dynlib: Lib, importc: "mdb_put".}
+
+proc mdb_env_set_mapsize(env: MDB_Env, size: uint64): cint {.cdecl, dynlib: Lib, importc: "mdb_env_set_mapsize".}
+
+type
+  LmdbChainDB* = ref object of RootObj
+    env: MDB_Env
+    txn: MDB_Txn
+    dbi: MDB_Dbi
+    manualCommit: bool
+
+  ChainDB* = LmdbChainDB
+
+# call txBegin and txCommit if you want to disable auto-commit
+proc txBegin*(db: ChainDB, manualCommit = true): bool =
+  result = true
+  if manualCommit:
+    db.manualCommit = true
+  else:
+    if db.manualCommit: return
+  result = mdb_txn_begin(db.env, MDB_Txn(nil), 0, db.txn) == 0
+  result = result and mdb_dbi_open(db.txn, nil, 0, db.dbi) == 0
+
+proc txCommit*(db: ChainDB, manualCommit = true): bool =
+  result = true
+  if manualCommit:
+    db.manualCommit = false
+  else:
+    if db.manualCommit: return
+  result = mdb_txn_commit(db.txn) == 0
+  mdb_dbi_close(db.env, db.dbi)
+
+proc toMdbVal(val: openArray[byte]): MDB_Val =
+  result.mv_size = val.len
+  result.mv_data = unsafeAddr val[0]
+
+proc get*(db: ChainDB, key: openarray[byte]): seq[byte] =
+  if key.len == 0: return
+  var
+    dbKey = toMdbVal(key)
+    dbVal: MDB_val
+
+  if not db.txBegin(false):
+    raiseKeyReadError(key)
+
+  var errCode = mdb_get(db.txn, db.dbi, dbKey, dbVal)
+
+  if not(errCode == 0 or errCode == MDB_NOTFOUND):
+    raiseKeyReadError(key)
+
+  if dbVal.mv_size > 0 and errCode == 0:
+    result = newSeq[byte](dbVal.mv_size.int)
+    copyMem(result[0].addr, dbVal.mv_data, result.len)
+  else:
+    result = @[]
+
+  traceGet key, result
+  if not db.txCommit(false):
+    raiseKeyReadError(key)
+
+proc put*(db: ChainDB, key, value: openarray[byte]) =
+  tracePut key, value
+  if key.len == 0 or value.len == 0: return
+  var
+    dbKey = toMdbVal(key)
+    dbVal = toMdbVal(value)
+
+  if not db.txBegin(false):
+    raiseKeyWriteError(key)
+
+  var ok = mdb_put(db.txn, db.dbi, dbKey, dbVal, 0) == 0
+  if not ok:
+    raiseKeyWriteError(key)
+
+  if not db.txCommit(false):
+    raiseKeyWriteError(key)
+
+proc contains*(db: ChainDB, key: openarray[byte]): bool =
+  if key.len == 0: return
+  var
+    dbKey = toMdbVal(key)
+    dbVal: MDB_val
+
+  if not db.txBegin(false):
+    raiseKeySearchError(key)
+
+  result = mdb_get(db.txn, db.dbi, dbKey, dbVal) == 0
+
+  if not db.txCommit(false):
+    raiseKeySearchError(key)
+
+proc del*(db: ChainDB, key: openarray[byte]) =
+  traceDel key
+  if key.len == 0: return
+  var
+    dbKey = toMdbVal(key)
+
+  if not db.txBegin(false):
+    raiseKeyDeletionError(key)
+
+  var errCode = mdb_del(db.txn, db.dbi, dbKey, nil)
+  if not(errCode == 0 or errCode == MDB_NOTFOUND):
+    raiseKeyDeletionError(key)
+
+  if not db.txCommit(false):
+    raiseKeyDeletionError(key)
+
+proc close*(db: ChainDB) =
+  mdb_env_close(db.env)
+
+proc newChainDB*(basePath: string): ChainDB =
+  result.new()
+
+  let dataDir = basePath / "nimbus.db"
+  var ok = mdb_env_create(result.env) == 0
+  if not ok: raiseStorageInitError()
+
+  ok = mdb_env_set_mapsize(result.env, LMDB_MAP_SIZE) == 0
+  if not ok: raiseStorageInitError()
+
+  # file mode ignored on windows
+  ok = mdb_env_open(result.env, dataDir, MDB_NOSUBDIR, 0o664) == 0
+  if not ok: raiseStorageInitError()
+
+  result.put(emptyRlpHash.data, emptyRlp)
diff --git a/tests/tracerTestGen.nim b/tests/tracerTestGen.nim
index d9bdb359b..b06476151 100644
--- a/tests/tracerTestGen.nim
+++ b/tests/tracerTestGen.nim
@@ -3,11 +3,11 @@ import
   eth_trie/[db], ../nimbus/db/[db_chain, capturedb],
   ../nimbus/[tracer, vm_types, config]
 
-const backEnd {.strdefine.} = "lmdb"
+const nimbus_db_backend {.strdefine.} = "rocksdb"
 
-when backEnd == "sqlite":
+when nimbus_db_backend == "sqlite":
   import ../nimbus/db/backends/sqlite_backend
-elif backEnd == "rocksdb":
+elif nimbus_db_backend == "rocksdb":
   import ../nimbus/db/backends/rocksdb_backend
 else:
   import ../nimbus/db/backends/lmdb_backend