diff --git a/parsers.go b/parsers.go
index 5ffcefe..d00b4af 100644
--- a/parsers.go
+++ b/parsers.go
@@ -33,6 +33,24 @@ type ProvingKeyString struct {
 
 type WitnessString []string
 
+func ParseWitness(wJson []byte) (Witness, error) {
+	var ws WitnessString
+	err := json.Unmarshal(wJson, &ws)
+	if err != nil {
+		return nil, err
+	}
+
+	var w Witness
+	for i := 0; i < len(ws); i++ {
+		bi, err := stringToBigInt(ws[i])
+		if err != nil {
+			return nil, err
+		}
+		w = append(w, bi)
+	}
+	return w, nil
+}
+
 func ParseProvingKey(pkJson []byte) (*ProvingKey, error) {
 	var pkStr ProvingKeyString
 	err := json.Unmarshal(pkJson, &pkStr)
diff --git a/testdata/provingkey.json b/testdata/provingkey.json
new file mode 100644
index 0000000..56acb28
--- /dev/null
+++ b/testdata/provingkey.json
@@ -0,0 +1,221 @@
+{
+ "protocol": "groth",
+ "nVars": 4,
+ "nPublic": 1,
+ "domainBits": 2,
+ "domainSize": 4,
+ "polsA": [
+  {
+   "1": "1"
+  },
+  {
+   "2": "1"
+  },
+  {
+   "0": "21888242871839275222246405745257275088548364400416034343698204186575808495616"
+  },
+  {}
+ ],
+ "polsB": [
+  {},
+  {},
+  {},
+  {
+   "0": "1"
+  }
+ ],
+ "polsC": [
+  {},
+  {
+   "0": "21888242871839275222246405745257275088548364400416034343698204186575808495616"
+  },
+  {},
+  {}
+ ],
+ "A": [
+  [
+   "16145916318196730299582072104388453231952213805668281741813587224450782397538",
+   "4434505318477484327659527264104806919103674231447634885054368605283938696207",
+   "1"
+  ],
+  [
+   "10618406967550056457559358662746625591602641004174976323307214433994084907915",
+   "1843236360452735081347085412539192450068665510574800388201121698908391533923",
+   "1"
+  ],
+  [
+   "1208972877970123411566574123860641832032384890981476033353526096830198333194",
+   "777503551507025252294438107100944741641946695980350712141258191590862204805",
+   "1"
+  ],
+  [
+   "0",
+   "1",
+   "0"
+  ]
+ ],
+ "B1": [
+  [
+   "0",
+   "1",
+   "0"
+  ],
+  [
+   "0",
+   "1",
+   "0"
+  ],
+  [
+   "0",
+   "1",
+   "0"
+  ],
+  [
+   "1208972877970123411566574123860641832032384890981476033353526096830198333194",
+   "21110739320332249969951967638156330347054364461317472950547779703054364003778",
+   "1"
+  ]
+ ],
+ "B2": [
+  [
+   [
+    "0",
+    "0"
+   ],
+   [
+    "1",
+    "0"
+   ],
+   [
+    "0",
+    "0"
+   ]
+  ],
+  [
+   [
+    "0",
+    "0"
+   ],
+   [
+    "1",
+    "0"
+   ],
+   [
+    "0",
+    "0"
+   ]
+  ],
+  [
+   [
+    "0",
+    "0"
+   ],
+   [
+    "1",
+    "0"
+   ],
+   [
+    "0",
+    "0"
+   ]
+  ],
+  [
+   [
+    "9283666785342556550467669770956850930982548182701254051508520248901282197973",
+    "11369378229277445316894458966429873744779877313900506577160370623273013178252"
+   ],
+   [
+    "10625777544326349817513295021482494426101347915428005055375725845993157551870",
+    "21401790227434807639472120486932615400751346915707967674912972446672152512583"
+   ],
+   [
+    "1",
+    "0"
+   ]
+  ]
+ ],
+ "C": [
+   ["0", "0", "0"],
+   ["0", "0", "0"],
+  [
+   "18545397130363256321926549041639729743141431075318462370025152832852939073307",
+   "2616861286119881509516846668252666108741377487742351180864484963773522850295",
+   "1"
+  ],
+  [
+   "2525636894222523143142808451978966577881491159416335121257094078801746645235",
+   "16535861715720884910945782094658684127457731006848459401043529763859412916301",
+   "1"
+  ]
+ ],
+ "vk_alfa_1": [
+  "16068200068882411629410035093795608526771554471937479213726134794660780102550",
+  "20501676791339890155108177259376873296876233680064261776170683533526889207340",
+  "1"
+ ],
+ "vk_beta_1": [
+  "5365573823291502335794132193185274277974617763863996013954364593194136465016",
+  "11644349101388223784378896360832586557929271772024496470708905460439243894584",
+  "1"
+ ],
+ "vk_delta_1": [
+  "15680151079584844532489259722917096938769907841931133291928746685613811358733",
+  "16784279394546603697881462850128771845781623009095957214568117820968443242506",
+  "1"
+ ],
+ "vk_beta_2": [
+  [
+   "13973091636763944887728510851169742544309374663995476311690518173988838518856",
+   "12903946180439304546475897520537621821375470264150438270817301786763517825250"
+  ],
+  [
+   "370374369234123593044872519351942112043402224488849374153134091815693350697",
+   "17423079115073430837335625309232513526393852743032331213038909731579295753224"
+  ],
+  [
+   "1",
+   "0"
+  ]
+ ],
+ "vk_delta_2": [
+  [
+   "1192908377564945353343974763532707545526009748811618581810344379529229172159",
+   "10373868200341234689659697947697825014338252335089936445608341428888724327154"
+  ],
+  [
+   "6258644116885726740914814071115026921733331135830050167672544002787860516536",
+   "2784479362505735918824286514153638713518597314121639212447411360814573899319"
+  ],
+  [
+   "1",
+   "0"
+  ]
+ ],
+ "hExps": [
+  [
+   "1137454402546542017796495169973321459788661791339116580816039119135416491226",
+   "10581992627412174102808274058339351114019966039682644500297077873241797449624",
+   "1"
+  ],
+  [
+   "3253811140290017934039655168718326971539049766532829948316663892796117200680",
+   "3496418280903365070403555364992889823060908616232765866481366503085657668823",
+   "1"
+  ],
+  [
+   "7426424892372059053157891943364774187577620238460342150964457392480230669997",
+   "14261604113665464620229095737623968407326243628348811684313201927885047569756",
+   "1"
+  ],
+  [
+   "14706800931196014592083141709960980909656368788497354451613143286705158867076",
+   "8321358240716309588423491516494287064322707776658072083979021495463106099808",
+   "1"
+  ],
+  [
+   "21560594640856118286219580794351895174554979903538723611152363886530011848778",
+   "15512645592267656573910252616175869133748229079507420222439452334013754939136",
+   "1"
+  ]
+ ]
+}
diff --git a/testdata/witness.json b/testdata/witness.json
new file mode 100644
index 0000000..59dd77b
--- /dev/null
+++ b/testdata/witness.json
@@ -0,0 +1,6 @@
+[
+ "1",
+ "33",
+ "3",
+ "11"
+]