diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index cc19885c7..d59fcaef1 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -4916,7 +4916,6 @@ struct TALER_EXCHANGE_AccountMergeResponse
       uint64_t requirement_row;
     } unavailable_for_legal_reasons;
 
-
   } details;
 
 };
@@ -5496,7 +5495,7 @@ TALER_EXCHANGE_reserves_attest (
 
 
 /**
- * Cancel a reserve status request.  This function cannot be used
+ * Cancel a reserve attestation request.  This function cannot be used
  * on a request handle if a response is already served for it.
  *
  * @param rah the reserve attest request handle
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index dc08c585d..959cdc7ed 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -62,6 +62,7 @@ libtalerexchange_la_SOURCES = \
   exchange_api_refund.c \
   exchange_api_reserves_get.c \
   exchange_api_reserves_history.c \
+  exchange_api_reserves_open.c \
   exchange_api_reserves_status.c \
   exchange_api_transfers_get.c \
   exchange_api_withdraw.c \
diff --git a/src/lib/exchange_api_reserves_open.c b/src/lib/exchange_api_reserves_open.c
new file mode 100644
index 000000000..8f3fab172
--- /dev/null
+++ b/src/lib/exchange_api_reserves_open.c
@@ -0,0 +1,493 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014-2022 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file lib/exchange_api_reserves_open.c
+ * @brief Implementation of the POST /reserves/$RESERVE_PUB/open requests
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP open codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_exchange_service.h"
+#include "taler_json_lib.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+
+/**
+ * @brief A /reserves/$RID/open Handle
+ */
+struct TALER_EXCHANGE_ReservesOpenHandle
+{
+
+  /**
+   * The connection to exchange this request handle will use
+   */
+  struct TALER_EXCHANGE_Handle *exchange;
+
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * Handle for the request.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Context for #TEH_curl_easy_post(). Keeps the data that must
+   * persist for Curl to make the upload.
+   */
+  struct TALER_CURL_PostContext post_ctx;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_EXCHANGE_ReservesOpenCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Public key of the reserve we are querying.
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+  /**
+   * Our signature.
+   */
+  struct TALER_ReserveSignatureP reserve_sig;
+
+  /**
+   * When did we make the request.
+   */
+  struct GNUNET_TIME_Timestamp ts;
+
+};
+
+
+/**
+ * We received an #MHD_HTTP_OK open code. Handle the JSON
+ * response.
+ *
+ * @param roh handle of the request
+ * @param j JSON response
+ * @return #GNUNET_OK on success
+ */
+static enum GNUNET_GenericReturnValue
+handle_reserves_open_ok (struct TALER_EXCHANGE_ReservesOpenHandle *roh,
+                         const json_t *j)
+{
+  struct TALER_EXCHANGE_ReserveOpenResult rs = {
+    .hr.reply = j,
+    .hr.http_status = MHD_HTTP_OK,
+  };
+  struct GNUNET_JSON_Specification spec[] = {
+    TALER_JSON_spec_amount_any ("open_cost",
+                                &rs.details.ok.open_cost),
+    GNUNET_JSON_spec_timestamp ("reserve_expiration",
+                                &rs.details.ok.expiration_time),
+    GNUNET_JSON_spec_end ()
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_JSON_parse (j,
+                         spec,
+                         NULL,
+                         NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  roh->cb (roh->cb_cls,
+           &rs);
+  roh->cb = NULL;
+  GNUNET_JSON_parse_free (spec);
+  return GNUNET_OK;
+}
+
+
+/**
+ * We received an #MHD_HTTP_PAYMENT_REQUIRED open code. Handle the JSON
+ * response.
+ *
+ * @param roh handle of the request
+ * @param j JSON response
+ * @return #GNUNET_OK on success
+ */
+static enum GNUNET_GenericReturnValue
+handle_reserves_open_pr (struct TALER_EXCHANGE_ReservesOpenHandle *roh,
+                         const json_t *j)
+{
+  struct TALER_EXCHANGE_ReserveOpenResult rs = {
+    .hr.reply = j,
+    .hr.http_status = MHD_HTTP_PAYMENT_REQUIRED,
+  };
+  struct GNUNET_JSON_Specification spec[] = {
+    TALER_JSON_spec_amount_any ("open_cost",
+                                &rs.details.payment_required.open_cost),
+    GNUNET_JSON_spec_timestamp ("reserve_expiration",
+                                &rs.details.payment_required.expiration_time),
+    GNUNET_JSON_spec_end ()
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_JSON_parse (j,
+                         spec,
+                         NULL,
+                         NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  roh->cb (roh->cb_cls,
+           &rs);
+  roh->cb = NULL;
+  GNUNET_JSON_parse_free (spec);
+  return GNUNET_OK;
+}
+
+
+/**
+ * We received an #MHD_HTTP_UNAVAILABLE_FOR_LEGAL_REASONS open code. Handle the JSON
+ * response.
+ *
+ * @param roh handle of the request
+ * @param j JSON response
+ * @return #GNUNET_OK on success
+ */
+static enum GNUNET_GenericReturnValue
+handle_reserves_open_kyc (struct TALER_EXCHANGE_ReservesOpenHandle *roh,
+                          const json_t *j)
+{
+  struct TALER_EXCHANGE_ReserveOpenResult rs = {
+    .hr.reply = j,
+    .hr.http_status = MHD_HTTP_UNAVAILABLE_FOR_LEGAL_REASONS,
+  };
+  struct GNUNET_JSON_Specification spec[] = {
+    GNUNET_JSON_spec_fixed_auto (
+      "h_payto",
+      &rs.details.unavailable_for_legal_reasons.h_payto),
+    GNUNET_JSON_spec_uint64 (
+      "requirement_row",
+      &rs.details.unavailable_for_legal_reasons.requirement_row),
+    GNUNET_JSON_spec_end ()
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_JSON_parse (j,
+                         spec,
+                         NULL,
+                         NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  roh->cb (roh->cb_cls,
+           &rs);
+  roh->cb = NULL;
+  GNUNET_JSON_parse_free (spec);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /reserves/$RID/open request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_ReservesOpenHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_reserves_open_finished (void *cls,
+                               long response_code,
+                               const void *response)
+{
+  struct TALER_EXCHANGE_ReservesOpenHandle *roh = cls;
+  const json_t *j = response;
+  struct TALER_EXCHANGE_ReserveOpenResult rs = {
+    .hr.reply = j,
+    .hr.http_status = (unsigned int) response_code
+  };
+
+  roh->job = NULL;
+  switch (response_code)
+  {
+  case 0:
+    rs.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
+    break;
+  case MHD_HTTP_OK:
+    if (GNUNET_OK !=
+        handle_reserves_open_ok (roh,
+                                 j))
+    {
+      GNUNET_break_op (0);
+      rs.hr.http_status = 0;
+      rs.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+    }
+    break;
+  case MHD_HTTP_BAD_REQUEST:
+    /* This should never happen, either us or the exchange is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    GNUNET_break (0);
+    rs.hr.ec = TALER_JSON_get_error_code (j);
+    rs.hr.hint = TALER_JSON_get_error_hint (j);
+    break;
+  case MHD_HTTP_PAYMENT_REQUIRED:
+    if (GNUNET_OK !=
+        handle_reserves_open_pr (roh,
+                                 j))
+    {
+      GNUNET_break_op (0);
+      rs.hr.http_status = 0;
+      rs.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+    }
+    break;
+  case MHD_HTTP_FORBIDDEN:
+    /* This should never happen, either us or the exchange is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    GNUNET_break (0);
+    rs.hr.ec = TALER_JSON_get_error_code (j);
+    rs.hr.hint = TALER_JSON_get_error_hint (j);
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    /* Nothing really to verify, this should never
+       happen, we should pass the JSON reply to the application */
+    rs.hr.ec = TALER_JSON_get_error_code (j);
+    rs.hr.hint = TALER_JSON_get_error_hint (j);
+    break;
+  case MHD_HTTP_UNAVAILABLE_FOR_LEGAL_REASONS:
+    if (GNUNET_OK !=
+        handle_reserves_open_kyc (roh,
+                                  j))
+    {
+      GNUNET_break_op (0);
+      rs.hr.http_status = 0;
+      rs.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+    }
+    break;
+  case MHD_HTTP_INTERNAL_SERVER_ERROR:
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    rs.hr.ec = TALER_JSON_get_error_code (j);
+    rs.hr.hint = TALER_JSON_get_error_hint (j);
+    break;
+  default:
+    /* unexpected response code */
+    GNUNET_break_op (0);
+    rs.hr.ec = TALER_JSON_get_error_code (j);
+    rs.hr.hint = TALER_JSON_get_error_hint (j);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u/%d for reserves open\n",
+                (unsigned int) response_code,
+                (int) rs.hr.ec);
+    break;
+  }
+  if (NULL != roh->cb)
+  {
+    roh->cb (roh->cb_cls,
+             &rs);
+    roh->cb = NULL;
+  }
+  TALER_EXCHANGE_reserves_open_cancel (roh);
+}
+
+
+struct TALER_EXCHANGE_ReservesOpenHandle *
+TALER_EXCHANGE_reserves_open (
+  struct TALER_EXCHANGE_Handle *exchange,
+  const struct TALER_ReservePrivateKeyP *reserve_priv,
+  const struct TALER_Amount *reserve_contribution,
+  unsigned int coin_payments_length,
+  const struct TALER_EXCHANGE_PurseDeposit *coin_payments,
+  struct GNUNET_TIME_Timestamp expiration_time,
+  uint32_t min_purses,
+  TALER_EXCHANGE_ReservesOpenCallback cb,
+  void *cb_cls)
+{
+  struct TALER_EXCHANGE_ReservesOpenHandle *roh;
+  struct GNUNET_CURL_Context *ctx;
+  CURL *eh;
+  char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
+  const struct TALER_EXCHANGE_Keys *keys;
+  json_t *cpa;
+
+  if (GNUNET_YES !=
+      TEAH_handle_is_ready (exchange))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  roh = GNUNET_new (struct TALER_EXCHANGE_ReservesOpenHandle);
+  roh->exchange = exchange;
+  roh->cb = cb;
+  roh->cb_cls = cb_cls;
+  roh->ts = GNUNET_TIME_timestamp_get ();
+  GNUNET_CRYPTO_eddsa_key_get_public (&reserve_priv->eddsa_priv,
+                                      &roh->reserve_pub.eddsa_pub);
+  {
+    char pub_str[sizeof (struct TALER_ReservePublicKeyP) * 2];
+    char *end;
+
+    end = GNUNET_STRINGS_data_to_string (
+      &roh->reserve_pub,
+      sizeof (roh->reserve_pub),
+      pub_str,
+      sizeof (pub_str));
+    *end = '\0';
+    GNUNET_snprintf (arg_str,
+                     sizeof (arg_str),
+                     "/reserves/%s/open",
+                     pub_str);
+  }
+  roh->url = TEAH_path_to_url (exchange,
+                               arg_str);
+  if (NULL == roh->url)
+  {
+    GNUNET_free (roh);
+    return NULL;
+  }
+  eh = TALER_EXCHANGE_curl_easy_get_ (roh->url);
+  if (NULL == eh)
+  {
+    GNUNET_break (0);
+    GNUNET_free (roh->url);
+    GNUNET_free (roh);
+    return NULL;
+  }
+  keys = TALER_EXCHANGE_get_keys (exchange);
+  if (NULL == keys)
+  {
+    GNUNET_break (0);
+    curl_easy_cleanup (eh);
+    GNUNET_free (roh->url);
+    GNUNET_free (roh);
+    return NULL;
+  }
+  cpa = json_array ();
+  GNUNET_assert (NULL != cpa);
+  for (unsigned int i = 0; i<coin_payments_length; i++)
+  {
+    const struct TALER_EXCHANGE_PurseDeposit *pd = &coin_payments[i];
+    struct TALER_CoinSpendSignatureP coin_sig;
+    struct TALER_CoinSpendPublicKeyP coin_pub;
+    const struct TALER_AgeCommitmentProof *acp = pd->age_commitment_proof;
+    struct TALER_AgeCommitmentHash ahac;
+    struct TALER_AgeCommitmentHash *achp = NULL;
+    json_t *cp;
+
+    if (NULL != acp)
+    {
+      TALER_age_commitment_hash (&acp->commitment,
+                                 &ahac);
+      achp = &ahac;
+    }
+    TALER_wallet_reserve_open_deposit_sign (&pd->amount,
+                                            &roh->reserve_pub,
+                                            roh->ts,
+                                            &pd->coin_priv,
+                                            &coin_sig);
+    GNUNET_CRYPTO_eddsa_key_get_public (&pd->coin_priv.eddsa_priv,
+                                        &coin_pub.eddsa_pub);
+
+    cp = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_allow_null (
+        GNUNET_JSON_pack_data_auto ("h_age_commitment",
+                                    achp)),
+      TALER_JSON_pack_amount ("amount",
+                              &pd->amount),
+      GNUNET_JSON_pack_data_auto ("denom_pub_hash",
+                                  &pd->h_denom_pub),
+      TALER_JSON_pack_denom_sig ("ub_sig",
+                                 &pd->denom_sig),
+      GNUNET_JSON_pack_data_auto ("coin_pub",
+                                  &coin_pub),
+      GNUNET_JSON_pack_data_auto ("coin_sig",
+                                  &coin_sig));
+    GNUNET_assert (0 ==
+                   json_array_append_new (cpa,
+                                          cp));
+  }
+  TALER_wallet_reserve_open_sign (reserve_contribution,
+                                  roh->ts,
+                                  expiration_time,
+                                  min_purses,
+                                  reserve_priv,
+                                  &roh->reserve_sig);
+  {
+    json_t *open_obj = GNUNET_JSON_PACK (
+      GNUNET_JSON_pack_timestamp ("request_timestamp",
+                                  roh->ts),
+      GNUNET_JSON_pack_timestamp ("reserve_expiration",
+                                  expiration_time),
+      GNUNET_JSON_pack_array_steal ("payments",
+                                    cpa),
+      TALER_JSON_pack_amount ("reserve_payment",
+                              reserve_contribution),
+      GNUNET_JSON_pack_uint64 ("min_purses",
+                               min_purses),
+      GNUNET_JSON_pack_data_auto ("reserve_sig",
+                                  &roh->reserve_sig));
+
+    if (GNUNET_OK !=
+        TALER_curl_easy_post (&roh->post_ctx,
+                              eh,
+                              open_obj))
+    {
+      GNUNET_break (0);
+      curl_easy_cleanup (eh);
+      json_decref (open_obj);
+      GNUNET_free (roh->url);
+      GNUNET_free (roh);
+      return NULL;
+    }
+    json_decref (open_obj);
+  }
+  ctx = TEAH_handle_to_context (exchange);
+  roh->job = GNUNET_CURL_job_add2 (ctx,
+                                   eh,
+                                   roh->post_ctx.headers,
+                                   &handle_reserves_open_finished,
+                                   roh);
+  return roh;
+}
+
+
+void
+TALER_EXCHANGE_reserves_open_cancel (
+  struct TALER_EXCHANGE_ReservesOpenHandle *roh)
+{
+  if (NULL != roh->job)
+  {
+    GNUNET_CURL_job_cancel (roh->job);
+    roh->job = NULL;
+  }
+  TALER_curl_easy_post_finished (&roh->post_ctx);
+  GNUNET_free (roh->url);
+  GNUNET_free (roh);
+}
+
+
+/* end of exchange_api_reserves_open.c */