diff --git a/include/common/fcgi.h b/include/common/fcgi.h
new file mode 100644
index 0000000..3560e0c
--- /dev/null
+++ b/include/common/fcgi.h
@@ -0,0 +1,117 @@
+/*
+ * include/common/fcgi.h
+ * This file contains FastCGI protocol definitions.
+ *
+ * Copyright (C) 2019 HAProxy Technologies, Christopher Faulet <cfaulet@haproxy.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _COMMON_FCGI_H
+#define _COMMON_FCGI_H
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <common/config.h>
+#include <common/standard.h>
+#include <common/buf.h>
+#include <common/ist.h>
+
+/* FCGI protocol version */
+#define FCGI_VERSION    0x1
+
+/* flags for FCGI_BEGIN_REQUEST records */
+#define FCGI_KEEP_CONN  0x01
+
+/* FCGI record's type */
+enum fcgi_record_type {
+	FCGI_BEGIN_REQUEST     =  1,
+	FCGI_ABORT_REQUEST     =  2,
+	FCGI_END_REQUEST       =  3,
+	FCGI_PARAMS            =  4,
+	FCGI_STDIN             =  5,
+	FCGI_STDOUT            =  6,
+	FCGI_STDERR            =  7,
+	FCGI_DATA              =  8,
+	FCGI_GET_VALUES        =  9,
+	FCGI_GET_VALUES_RESULT = 10,
+	FCGI_UNKNOWN_TYPE      = 11,
+	FCGI_ENTRIES
+} __attribute__((packed));
+
+enum fcgi_role {
+	FCGI_RESPONDER  = 1,
+	FCGI_AUTHORIZER = 2, /* Unsupported */
+	FCGI_FILTER     = 3, /* Unsupported */
+} __attribute__((packed));
+
+/* Protocol status */
+enum fcgi_proto_status {
+	FCGI_PS_REQUEST_COMPLETE = 0,
+	FCGI_PS_CANT_MPX_CONN    = 1,
+	FCGI_PS_OVERLOADED       = 2,
+	FCGI_PS_UNKNOWN_ROLE     = 3,
+	FCGI_PS_ENTRIES,
+} __attribute__((packed));
+
+struct fcgi_header {
+	uint8_t  vsn;
+	uint8_t  type;
+	uint16_t id;
+	uint16_t len;
+	uint8_t  padding;
+	uint8_t  rsv;
+};
+
+struct fcgi_param {
+	struct ist n;
+	struct ist v;
+};
+
+struct fcgi_begin_request {
+	enum fcgi_role role;
+	uint8_t flags;
+};
+
+struct fcgi_end_request {
+	uint32_t status;
+	uint8_t  errcode;
+};
+
+struct fcgi_unknown_type {
+    uint8_t type;
+};
+
+
+
+int    fcgi_encode_record_hdr(struct buffer *out, const struct fcgi_header *h);
+size_t fcgi_decode_record_hdr(const struct buffer *in, size_t o, struct fcgi_header *h);
+
+int    fcgi_encode_begin_request(struct buffer *out, const struct fcgi_begin_request *r);
+
+int    fcgi_encode_param(struct buffer *out, const struct fcgi_param *p);
+size_t fcgi_decode_param(const struct buffer *in, size_t o, struct fcgi_param *p);
+size_t fcgi_aligned_decode_param(const struct buffer *in, size_t o, struct fcgi_param *p);
+
+size_t fcgi_decode_end_request(const struct buffer *in, size_t o, struct fcgi_end_request *r);
+
+#endif /* _COMMON_FCGI_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */